University  of  California 

DEFT.  OF  MINING  METALLURGY 


STEAM  SHO.VEL  MINING 


%  Qraw-MlRook  &  7m 


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STEAM  SHOVEL  MINING* 

INCLUDING  A 

CONSIDERATION  OF 

ELECTRIC  SHOVELS  AND  OTHER 

POWER  EXCAVATORS 

IN  OPEN-PIT  MINING 


BY 
ROBERT  MARSH,  JR. 

il 


FIRST  EDITION 


McGRAW-HILL  BOOK  COMPANY,  INC. 

NEW  YORK:     239   WEST  39TH  STREET 

LONDON:    6  &  8  BOUVERIE  ST.,  E.  C.  4 

1920 


COPYRIGHT,  1920,  BY  THE 
MCGRAW-HILL  BOOK  COMPANY,  INC. 


*.»•  •  *•  ••     •  •*.*•  *  * 

»«•»*  •  »»•»  •  • 


p  R  K  H  S    YORK 


^Dedicated  to 

POPE  YEATMAN 

to  whom  for  his  constant  encouragement  and 
example  the  author  is  deeply  indebted. 


4252 16 


PREFACE 

The  purpose  of  this  volume  is  to  present  in  a  collected  and 
condensed  form  the  general  information  covering  the  develop- 
ment and  study  of  such  mining  problems  as  may  best  be  solved 
by  the  application  of  open-pit  methods  involving  the  use  of 
modern  power-excavators.  It  is  assumed  that  the  reader  has 
a  general  idea  of  mining  practice. 

Compared  with  the  broad  old  science  of  mining,  the  application 
of  the  power-shovel  is  relatively  new,  and  perhaps  for  that 
reason,  information  concerning  its  use  is  not  so  widely  known. 
The  majority  of  those  in  charge  of  such  operations  are  practical 
men  little  given  to  writing.  Many  have  been  drawn  from  in- 
dustrial and  constructive  engineering  fields  rather  than  from 
mining,  and  some  are  at  times  inclined  to  guard  the  details  of 
successful  methods  which  have  been  gained  only  after  long 
experience.  It  is  therefore  the  purpose  here  to  analyze,  compare 
and  criticise  such  information  on  the  subject,  as  the  writer  has 
accumulated  through  reading,  travel  and  operation  of  open-pit 
work,  with  the  aim  of  making  this  information  as  helpful  as  possible 
to  the  profession  of  which  the  writer  is  happy  to  belong.  It  will 
be  noted  that  emphasis  is  laid  only  on  such  power-shovel  work 
as  pertains  to  mining,  rather  than  to  include  the  broad  field  of 
general  excavation  work,  though  in  many  cases  the  operations 
are  conducted  in  much  the  same  way.  Mining  operations  are 
however  of  a  destructive  character  and  much  less  attention 
need  usually  be  paid  to  the  aftermath  of  the  excavations  or  to  the 
final  disposal  of  the  debris.  The  direct  object  is  the  winning 
of  the  ore,  efficiently  and  cheaply,  not  the  construction  of  an 
engineering  monument  of  utility. 

The  prices  of  steam-shovels  and  other  machinery  and  supplies, 
given  in  this  book,  are  based  on  1915-1917  quotations  and  are 
believed  to  be  more  useful  than  present  day  prices,  which  are 
regarded  as  unstable.  Firms  contemplating  purchases  should 
solicit  from  manufacturers  their  latest  quotations,  but  for  com- 
parative purposes  the  prices  given  in  the  text  are  believed  to  be 
safest. 

vii 


viii  PREFACE 

I  wish  to  make  the  fullest  acknowledgment  for  the  assistance 
that  has  been  received  in  gathering  this  information.  It  has 
come  from  pit  and  shovel  men,  from  their  foremen  and  super- 
intendents, from  the  builders  of  the  machinery  and  equipment, 
from  engineering  periodicals  and  books,  and  from  those  engineers 
with  whom  I  'have  had  the  great  pleasure  and  advantage  of  as- 
sociation for  the  past  twelve  years.  I  also  wish  to  express  my 
gratitude  and  appreciation  for  the  work  done  by  my  friend 
Mr.  E.  Coppee  Thurston  in  reading  and  correcting  the  manu- 
script and  proof  sheets. 


CONTENTS 

PAGE 

PREFACE v 

CHAPTER  I 

THE  POWER  SHOVEL 1 

Introduction  to  Mining  Operations — Early  Open-cast  Work — 
Transition  at  Rio  Tinto,  Spain — Early  Application  to  Mining — 
Mechanical  Development — Invention  and  Patents — Description 
of  Standard  Shovel — Modern  Standard  Construction — The  Rail- 
road or  Standard  Type — The  Revolving  Type — Special  Construc- 
tion— Extra  Long  Booms  and  Dipper  Sticks — Quarry,  Tunnel  and 
Stope  Shovels — Wire  Rope  Shovels — Electric-driven  Shovels — 
Electro-hydraulic-driven  Shovels — Oil-engine-driven  Shovel — 
Competing  Machines — General  Field — Dredges — Dragline  Ex- 
cavators. 

CHAPTER  II 

MECHANICAL  EQUIPMENT , 44 

General  Conditions  Governing  a  Selection — Shovels — Principal 
Governing  Factors — Pit  Working  Conditions — Class  of  Operating 
Labor — Power — Steam — Electric-alternating  Current  vs.  Direct 
Current — Compressed  Air — Oil  Engines — Competing  Machines — 
Cost  of  Shovels — Locomotives — General  Governing  Conditions 
— Direct-connected  Steam  Type — Determination  of  Tractive 
Force — Factor  of  Adhesion — Resistance  Due  to  Grades — Re- 
sistance Due  to  Rolling  Friction — Resistance  Due  to  Curves — 
Hauling  Capacity — Horse  Power — Fuel  and  Water  Consumption — 
Usual' Sizes  for  Open-pit  Mining — Cost  of  Locomotives — Geared 
Types — Compressed  Air  Locomotives — General  Considerations — 
Cost  of  Installation  and  Operation  of  Air  Haulage — Electric  Loco- 
motives^— Trolley  System — Centrally  Controlled  Systems — The 
Woodford  System — Cars — Stripping  Cars — Platform  Type — 
Gondola  Type — Dumping  Type — Air  and  Hand  Operated — Ore 
Cars — Hopper-bottom  and  Gondolas — Track — General  Pit  Track 
— Definitions  and  Rules — Alignment — Curves — Maintenance — 
Materials  and  Equipment — General  Requirements — Rail — 
Fastenings  and  Accessories — Ties — Frogs  and  Switches — Protec- 
tive Devices— Drills— Churn  Drills— Tripod  Drills— Drills  for 
Block-holing — Miscellaneous  Equipment — Pumps — Illumination 
for  Night  Work — Telephones  and  Signals — Locomotive  Crane — Re- 
pair Car — Employees'  Car — Coaling  Car — Powder  Cars — General 

ix 


x  CONTENTS 

PAGE 

Utility  Cars — Wagons  and  Trucks — Shops — Machine  Shop — 
Blacksmith  and  Forge — Engine  and  Car  Shops — Electrician's 
Shop — Carpenter  Shop — Foundry — Sampling,  Assaying  and 
Engineering — Balance  in  Equipment — Life  of  Equipment — Coarse 
Crushers — Ore  Dryers. 

CHAPTER  III 

METHODS  OF  ATTACK 115 

General  Problems — Bench  Work — Height  of  Banks — Width  of 
Benches— Pit  Slopes — Slides — Casting  Over — Thorough  Cut — First 
Cut  Location — Course  Staking — Pit  Layouts — Spirals — Switch- 
backs— Tees  and  Wyes — Tunnels  and  Shafts — Inclined  Planes — 
Milling  System. 

CHAPTER  IV 

DRILLING  AND  BLASTING 135 

Hand  Drills — Machine-drills — Churn-drills — Use  and  Examples 
in  Blasting — Spacing  of  Holes — Systems  of  Shooting — Breaking 
Oversize  Material — Various  Explosives  Used — Calculation  of 
Charges — Detonators — Tamping— Safety  Rules — Gopher  Holes 
— Use  and  Examples  in  Blasting — Storing  and  Thawing  Explosives 
— Care  in  Use  of  Explosives. 

CHAPTER  V 

DISPOSAL  OF  MATERIAL 167 

Transportation — Trackage  Arrangements — Delays — Distribution 
of  Equipment — Routing  of  Overburden — Distribution  of  Crews — 
Use  of  Salt  Solution — Economy  in  Using  Large  Cars — Estimating 
Cost  to  New  Dump — Pit  Haulage  on  Mesabi  and  Elsewhere — 
Dumps — General  Problem — Hillside  and  Escarpment  Dumps — 
Mesabi  Dumps — Trestle  Dumps — Slush  Dumps — Swamp  and 
Lake  Dumps — Dumps  on  Caved  Ground — Copper  Mine  Dumps^ — 
Height  of  Dumps — Hydraulicking. 

CHAPTER  VI 

THE  DETERMINATION  OF  A  POWER  SHOVEL  MINE  .    .........   180 

Preliminary  Data  Required — Maps  and  Sections— Local  Costs  and 
Conditions— Initial  Time  and  Capital  Required — Other  General 
Considerations — Sound  Conclusion  on  Method  to  be  Recommended 
—Illustrative  Example  of  the  Solution  of  a  Problem — Hypothesis — 
Engineering  Calculations — Consideration  of  Shovel  Methods — 
Consideration  of  Underground  Methods — Top-slicing — Shrinkage 
— Stope  Method — Block-caving — Branch-raise  System — Esti- 
mated Grade  of  Ore  which  can  be  Worked  and  Yield  a  Profit — 
Consideration  of  Profits  from  Lower  Grade  Material — Comparative 
Re"sum6  of  Estimated  Profits  Derivable — Conclusion  and  Remarks 
— Special  Problems. 


CONTENTS  xi 

CHAPTER  VII 

PAGE 

COST  OP  SHOVEL  WORK 216 

Introduction — Wage  Scales — Examples '  of  Cost — Nevada  Con. 
Copper  Co. — Utah  Copper  Co. — Chino  Copper  Co. — Chile  Copper 
Co. — Mesabi  Iron  Ores — Miscellaneous  Work — Anthracite  Strip- 
ping— Yukon  Gold  Co. — Panama  Canal — Keeping  of  Cost  Records 
— Graphic  Records — Off  ce  Tabulations — Annual  Reports. 

CHAPTER  VIII 

ADMINISTRATION 240 

Introduction — Ratio  of  Output — Example — Lowest.  Grade  of  Ore 
that  Should  be  Worked— Amount  of  Prepaid  Stripping — Engineer- 
ing jWork — Labor. 

INDEX  .   251 


STEAM  SHOVEL  MINING 


CHAPTER  I 

THE  POWER  SHOVEL 
INTRODUCTION  TO  MINING  OPERATIONS 

Early  Open-Cast  Work. — Since  the  earliest  time  recorded,  min- 
ing has  been  carried  on  from  open-pits  or  "  glory-holes."  In  some 
places  the  ore-bodies  could  be  removed  directly  from  the  surface, 
but  more  often  it  was  necessary  to  remove  valueless  material 
from  the  top  before  much  of  the  ore  could  be  won,  and  later,  as 
depth  was  gained,  valueless  material  had  to  be  removed  from  the 
side  slopes.  Before  the  invention  of  excavating  machinery,  this 
work  was  slowly  performed  by  human  labor.  In  those  early 
times  much  of  the  work  was  done  by  slaves,  and  all  classes  of 
human  labor  was  indeed  cheap  in  comparison  with  present 
labor.  Without  the  assistance  of  perfected  excavating  machin- 
ery it  would  now  be  unprofitable  to  work  many  ore  deposits 
which  are  to-day  being  profitably  exploited,  and  many  others 
would  yield  only  a  small  part  of  the  profit  they  now  yield. 

Transition  at  Rio  Tinto,  Spain. — One  of  the  oldest  and  most 
interesting  examples  of  open-cast  work  is  found  at  Rio  Tinto, 
Province  of.  Andalusia,  southern  Spain.  This  district  was 
known  as  Tarshish  in  the  Bible  and  as  Tartessus  in  classic  days, 
and  to  it  is  attributed  the  silver  and  much  of  the  gold  which 
formed  the  mainstay  of  the  wealth  of  Tyre.  Thus  its  history 
dates  from  the  remotest  antiquity,  when  it  was  worked  by  the 
Phoenicians,  and  later  by  the  Romans. 

These  ore  deposits  are  essentially  great  lenticular  bodies  of 
copper-bearing  iron  pyrites,  but  their  upper  portions  were'  so 
enriched  by  decomposition  that  they  yielded  good  returns  in 
silver  and  gold,  and  in  enriched  copper  ores  which  were  smelted 
in  little  furnaces.  Great  heaps  of  old  slag  found  about  the 
mines  testify  to  the  large  amount  of  ore  extracted  and  the  excel- 
lence of  the  metallurgy,  the  labor  of  which  must  have  covered 

1 


SHOVEL  MINING 


a  long  period.  l  PaVt  of  this  work  was  in  the  form  of  open-casts, 
as  they  are  termed,  and  part  was  underground  galleries. 


After  a  time  of  inactivity  these  mines  were  again  exploited 
by  the  Spaniards,  but  they  had  a  rather  checkered  career 
until  1872  when  those  at  Rio  Tinto  were  sold  to  London  and 


THE  POWER  SHOVEL  3 

Bremen  capitalists.  The  new  owners  continued  to  work  the 
open-casts  with  hand-labor,  but  with  the  cost  of  production 
steadily  increasing.  The  owners  of  other  mines  in  the  district 
employed  the  same  method,  and  even  until  1911,  when  the 
writer  visited  the  district,  the  Zarza  mine  of  the  Tharsis  Com- 
pany was  being  so  worked  in  the  open-cast  portion.  Increasing 
depth  and  higher  cost  of  labor  have  forced  the  operators  to  seek 
more  economical  methods  with  the  result  that  the  Rio  Tinto 
Company  has  adopted  steam-shovel  methods;  the  Tharsis 
Company,  because  of  its  topography,  has  developed  and  adopted 
underground  mining  methods.  A  study  of  these  mines  serves 
well  to  exemplify  the  history  of  open-cast  mining  from  the  earliest 
to  the  present  time.  Figs.  1  and  2  illustrate  the  appearance 
in  September  1911  of  two  of  the  Rio  Tinto  pits.  The  first  is 
called  the  North  Lode  open-cast  and  illustrates  the  work  done 
by  hand-labor;  the  second  is  looking  westerly  into  the  Dionisio 
open-cast  and  shows  the  work  being  done  with  steam-shovels. 

Early  Application  to  Mining. — The  steam-shovel  has  been  in 
limited  use  since  about  1865  and  in  general  use  since  about 
1884.  At  first  it  was  employed  in  making  railroad  cuts  and  in 
excavating  many  classes  of  material  for  different  constructive 
purposes.  It  is  stated1  that  some  hand  stripping  was  conducted 
in  the  anthracite  regions  of  Pennsylvania  as  early  as  1864  and 
more  extensively  in  1874,  but  not  until  1887  was  the  first  steam- 
shovel  introduced  for  this  purpose.  This  shovel  was  one  of  the 
early  types  of  Oswego  shovel  weighing  30  to  35  tons.  Since 
then  shovels  have  come  rapidly  into  use  for  stripping  anthracite 
coal  veins.  Not  until  1892  does  it  appear  that  steam-shovels 
were  introduced  for  mining  ore,  but  in  that  year  a  steam-shovel 
was  shipped  to  the  town  of  Biwabik,  on  the  Mesabi  range,  to  be 
used  for  excavating  the  overburden  covering  deposits  of  iron  ore. 
The  Bucyrus  Company  states  that  its  first  shipment  of  steam- 
shovels  to  mining  companies  was  in.  April  1890,  when  several 
were  shipped  to  the  Michigan  iron  country.  The  year  following, 
and  as  iron-bearing  properties  continued  to  be  developed  in 
Minnesota  and  Michigan,  the  company  shipped  steam-shovels 
with  reasonable  regularity  to  many  mining  companies. 

The  first  shovel  sent  to  the  Mesabi  range  was  hauled  in  by 
wagons  and  was  a  small  machine,  but  the  following  year  a 
twenty-seven  ton  shovel  was  put  to  work;  from  that  time  until 

1  Warriner,  J.  B.:  Anthracite  Stripping,  T.A.I.M.E.,  1916,  pp.  33-60. 


STEAM  SHOVEL  MINING 


THE  POWER  SHOVEL  5 

the  present,  steam-shovels  have  taken  a  remarkable  part  in  the 
uncovering  and  mining  of  iron  ore. 

The  success  achieved  on  the  iron  ranges  was  so  marked  that 
it  was  decided  to  introduce  steam-shovel  methods  for  mining 
some  of  the  large  deposits  of  low-grade  copper  ore.  In  1904 
the  Bucyrus  Company  shipped  some  shovels  to  the  Rio  Tinto 
Company  in  Spain;  in  August  1906  shovels  were  started  strip- 
ping overburden  from  copper-bearing  porphyry  ore  at  Bingha'm, 
Utah,  now  owned  by  the  Utah  Copper  Company;  in  1907  they 
were  put  on  similar  work  near  Ely,  Nev.,  by  the  Nevada  Con- 
solidated Copper  Company;  and  later  at  Santa  Rita,  N.  Mex., 
by  the  Chino  Copper  Company.  During  the  years  1914-1916 
eight  shovels,  operated  by  electricity,  have  been  shipped  from 
the  United  States  to  Kiiruna,  Sweden,  for  use  in  the  magnetite 
mines  of  the  Loussavaara-Kiirunavaara  Aktiebolag;  several 
have  been  shipped  to  the  Belgian  Congo  for  use  in  the  copper 
mines  of  the  Union  Miniere  du  Haut  Katanga,  at  Kambove; 
several  are  at  work  on  the  great  deposit  of  copper  ore  at  Chuqui- 
camata,  Chile,  owned  by  tjie  Chile  Copper  Company;  and  many 
others  have  been  started  on  mining  work  of  a  similar  nature. 
A  recent  application  of  power  shovels  in  mining  is  that  of  strip- 
ping and  mining  shallow  deposits  of  coal  in  Kansas  and  Illinois. 
This  was  begun  in  1911  near  Danville,  111.,  at  the  property  of  the 
Mission  Mining  Company,  and  has  been  widely  extended  with 
the  perfecting  of  the  great  revolving  shovels.  In  the  anthracite 
fields  of  Pennsylvania,  the  shovel  equipment  has  remained 
largely  of  the  70  and  80-ton  type  but  the  successful  use  of  large 
drag-line  excavators,  weighing  about  255  tons  and  operated 
electrically,  would  indicate  a  field  for  the  large  revolving  steam- 
shovels  such  as  have  been  installed  near  Steubenville,  Ohio, 
and  in  the  Kansas  coal  fields.  Several  large  revolving  shovels 
are  also  being  used  by  the  Hydro-electric  Commission  of  Canada, 
digging  the  big  power  canal  at  Niagara  Falls. 

MECHANICAL  DEVELOPMENT 

Invention  and  Patents. — The  first  steam-shovel  is  said  to  have 
been  designed  and  patented  by  a  Mr.  Otis,  about  1840,  and  a 
few  of  crude  design  were  built  about  1864  by  the  Otis  Company 
of  Boston.  It  was  not  until  then  that  these  excavators  came  into 
even  limited  use,  and  not  until  about  1884  that  they  began  to 


6  STEAM  SHOVEL  MINING 

play  an  important  part  in  all  classes  of  excavation.  From  that 
time  to  the  present  day,  gradual  but  continuous  improvements 
have  been  made  in  the  design  of  the  mechanical  construction, 
boilers  and  engines.  A  history  of  the  United  States  patents  on 
them  may  be  found  in  Sub-class  No.  16,  Excavators,  Dippers, 
under  No.  37,  Excavating,  which  sub-class  contains  approxi- 
mately 462  patents.  Copies  of  these  may  be  obtained  from  the 
United  States  Patent  Office,  Washington,  D.  C. 

Description  of  Standard  Shovel. — The  power  shovel  is  classed 
as  an  up-digging  excavator,  designed  to  excavate  earth,  broken 
or  loosened  rock  and  ores,  gravel  and  other  material.  To  ac- 
complish this,  the  machine  has  been  designed  to  imitate  in  a 
mechanical  way,  the  motions  gone  through  by  a  man  shovelling. 
Reduced  to  the  simplest  form  there  are  three  movements;  the 
first  consists  in  advancing  the  excavating  tool  to  contact  with 
the  material  to  be  removed,  and  always  acts  in  a  vertical  plane; 
the  second  (aided  by  the  first)  fills  the  excavator  and  elevates 
it,  acting  in  a  vertical  plane;  the  third  swings  the  loaded  elevated 
excavator  laterally  and  in  a  horizontal  plane.  These  three  motions 
are  called  crowding,  hoisting  and  swinging,  each  is  reciprocal, 
and  each  may  act  independently,  or  two  or  all  three  motions  may 
act  simultaneously,  or  with  overlapping  motion  periods.  For 
convenience  in  moving  the  machine  from  place  to  place  it  is 
usually  equipped  with  a  self-propelling  mechanism  which  drives 
it  backwards  or  forwards  on  its  own  wheels.  Such  movement 
is  technically  called  "moving-up"  or  "  moving-back. "  To 
discharge  the  filled  elevated  excavator,  the  bottom,  which  is 
hinged  and  latched,  is  tripped,  permitting  the  material  to  fall 
through. 

The  general  construction  and  arrangement  of  the  various  makes 
of  standard  power  shovels  is  essentially  the  same.  The  follow- 
ing description,  illustrated  by  Fig.  3,  is  intended  to  cover,  in 
a  general  way,  what  may  be  classed  as  a  standard  steam-shovel, 
though  many  special  features  and  variations  in  construction  are 
found  in  the  different  types  and  makes.  The  principal  parts  of 
such  a  shovel  are: 

Car  Frame. — Upon  this  rests  the  operating  machinery  and 
power  equipment.  It  is  subjected  to  great  strain  and  shock, 
especially  at  the  front  end,  and  must  be  of  the  strongest  construc- 
tion. It  is  built  of  steel  I-beam  sills,  running  the  full  length  of 
the  car,  and  made  rigid  by  cast-steel  separators  drawn  tight  by 


THE  POWER  SHOVEL 


bolts  passing  entirely  through  the  car  from  side  to  side.  The 
deck  is  covered  with  steel  plates.  The  front  end  may  well  con- 
sist of  a  heavy  ribbed  casting  so  built  as  to  greatly  strengthen 
the  I-beams  and  give  the  deck  great  rigidity. 


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The  frame  is  mounted  on  two  all-steel  extra  heavy  trucks  of 
M.  C.  B.  standard  with  diamond  frames.  The  inside  axles  of 
both  trucks,  and  sometimes  all  four  axles,  are  keyed  to  sprocket 


8  STEAM  SHOVEL  MINING 

wheels,  chain-connected  to  a  drive  sprocket  wheel  for  propelling 
the  shovel. 

The  frame  supports  a  housing  of  timber  on  a  steel  framework. 
The  roof  is  often  armored  with  steel  plate  to  protect  the  crew 
and  machinery  from  falling  rocks. 

A-Frame.—  This  is  mounted  on  the  front  end  of  the  deck,  is 
supported  by  the  A-Frame  sill,  and  is  guyed  by  the  head-casting. 
It  is  built  of  two  heavy  square  steel  posts.  The  feet  of  the  posts 
are  drilled  to  take  through-bolts  for  fastening  to  sill  clevises. 
The  heads  are  often  joined  to  the  head  casting  by  being  babbitted 
in  the  recesses  provided  for  them.  The  A-frame  is  inclined 
slightly  forward  and  is  much  shorter  than  the  boom.  Joined 
to  the  head  casting  is  the  A-frame  back  leg,  a  solid  steel  tension 
member  which  supports  the  A-frame  and  is  fastened  over  the 
rear  trucks  of  the  car. 

Jack-Arms. — These  may  virtually  form  a  continuation  of  the 
A-frame  posts,  or,  in  very  large  shovels,  may  spring  from  the 
head-casting.  They  are  stabilizers  used  to  prevent  the  front 
end  of  the  car  from  tipping  sidewise  as  the  boom  and  dipper 
swing  from  side  to  side.  They  are  made  of  cast  or  structural 
steel;  the  upper  or  compression  member  is  fastened  to  the  A-frame 
supports,  the  lower  or  tension  member  is  secured  under  the  deck, 
and  the  lower  ends  of  both  members  carry  a  screw-jack  which 
is  readily  raised  or  lowered  to  get  a  bearing  on  the  jack  blocking. 
The  wider  spread  obtained  by  the  jack-arms  is  equivalent  to 
widening  the  track  gauge  to  the  same  distance,  and  thus  makes 
for  great  stability. 

Boom. — In  front  of  the  A-frame  sill  is  the  base  casting  carrying 
a  large  vertical  journal,  serving  as  a  pivotal-bearing  for  the 
swing-circle  and  boom,  and  forming  the  axis  of  rotation  for 
the  third  motion  of  the  shovel.  The  lower  end  of  the  boom  rests 
on  the  swing-circle  and  both  revolve  together  through  an  arc 
of  from  180°  to  240°.  The  upper  end  is  supported  by  the  boom 
support  guys,  made  of  steel  rods  or  bars.  The  boom  is  made  of 
two  parallel  armored-wood  (or  all  steel)  members  normally 
inclined  at  an  angle  of  about  40°  and  so  separated  as  to  allow  the 
free  passage  of  the  dipper  handle. 

A  study  of  the  figure  formed  by  the  deck,  boom,  A-frame, 
A-frame  back  legs  and  boom  support  guys  shows  it  to  be  a  diamond 
truss;  when  digging  straight  ahead  the  first  two  members  are 
in  compression  and  the  last  two  are  in  tension,  while  the  A-frame 


THE  POWER  SHOVEL 


9 


acts  as  a  compression  strut  between  the  chords.  When  digging 
to  the  right  or  left  of  the  shovel  axis,  the  truss  diagram  changes. 
The  A-frame  leg  farthest  from  the  dipper  becomes  a  tension 
member,  the  nearby  leg  remains  in  compression,  and  a  compres- 
sion strain  is  thrown  across  the  deck.  Fig.  41  gives  a  graphic  idea 
of  this,  it  being  a  strain  diagram  illustrating  the  strains  in  a  60- 
ton  shovel. 

Dipper  Handle. — The  dipper  handle,  or  stick,  is  also  an  armored 
wood  member,  usually  made  up  of  two  parallel  parts,  which 
plays  between  the  two  boom  members.  To  the  lower  end  is 
attached  the  dipper,  and  on  its  lower  face  are  fastened  two  parallel 
manganese-steel  racks  by  which  it  is  run  in  and  out  by  the  man- 
ganese-steel pinions  on  the  shipper  shaft.  The  dipper  handle 


f  Engines  10'xW Geared  5  to  t 

I  Drum  l8"Diam*5.S'Cir.foC«nhrof Chain 

Boiler  Pressure  I00lb.*90ll>. 

PUIIonChain.  18*x90"'*4.66*. 

\L  ess  IS*. '"for Friction  c/fty&Drui 


Ttnsion  17,500 
C  ly          From  Wf  of  Boom  1,500 


Ell 


FIG.  4. — Strain  diagram  of  standard  60-ton  steam  shovel. 

is  always  held  in  contact  with  these  pinions  by  means  of  the 
yoke  block. 

Dipper. — The  dipper  is  scoop  shaped,  with  a  digging  lower 
edge  and  an  ingeniously  hinged  door  for  a  bottom.  It  is  sub- 
jected to  the  severest  wear  and  so  the  front,  or  even  the  whole 
dipper,  is  often  made  of  manganese-steel.  The  lip  is  either  in  the 
form  of  a  cutting  edge  for  soft  material,  or  else  is  provided  with 
four  heavy  manganese-steel  teeth,  or  points,  for  hard  digging. 
The  bottom  is  hinged  with  special  hinges  fastened  to  the  lower 
part  of  the  back,  and  is  closed  by  a  spring  lug-latch  on  the  front 
side.  It  is  opened  by  the  craneman  pulling  on  a  light  line  operat- 
ing a  lever  to  which  the  latch  is  attached,  and  thus  dumping 
the  load  where  desired.  The  capacity  of  the  dipper  ranges  from 
one-half  to  eight  cubic  yards,  and  depends  on  the  size  of  the 
shovel  and  the  character  of  the  material  being  excavated.  It  is 

1  ROBINSON,  A.  W.:  The  Steam  Shovel  in  Mining,  P.L.S.M.I.,  Vol.  IV, 
pp.  59-68. 


10  STEAM  SHOVEL  MINING 

attached  to  the  dipper  handle  by  steel  arms  and  is  provided  with 
a  hinged  bail,  which  is  fastened  to  the  dipper  sheave  block,  and  by 
which  it  is  hoisted.  Fig.  5  illustrates  the  Vanderhoef  all-man- 
ganese-steel 4-cubic  yard  dipper,  which  has  given  good  results 
in  severe  work.  Such  a  dipper  will  have  a  life  of  at  least  one 
million  cubic  yards  of  medium  hard  material. 

Engines.— These  usually  consist  of  three  separate  engines 
of  the  double  cylinder  horizontal  type.  They  control  the  three 
working  movements,  crowding,  hoisting  and  swinging  and  are  so 


FIG.  5. — Vanderhoef  all  manganese-steel  dipper. 

termed.  The  crowding,  or  thrusting  engine  is  mounted  on  the 
upper  side  of  the  boom,  is  reversible,  and  is  controlled  by  the 
craneman.  Its  connecting  rods  rotate  a  crank  shaft  to  the  ends 
of  which  are  keyed  steel  pinions;  these  engage  with  the  shipper 
shaft  gears  rotating  the  shipper  shaft.  The  shipper  shaft  is 
provided  with  manganese-steel  pinions  which  track  with  the 
dipper  handle  racks  and  thus  run  the  dipper  in  or  out,  giving 
it  the  first  motion.  The  gears  and  pinions  have  square  holes 
to  fit  the  square  section  of  the  shipper  shaft,  thus  doing  away 
with  troubles  of  keying. 


THE  POWER  SHOVEL  11 

The  hoisting  engine  is  of  the  double  horizontal  type,  with 
Stephenson  link  motion.  As  it  does  heavy  hoisting,  it  is  the 
most  powerful  of  the  three.  The  engine  shaft  is  fitted  with 
counter-balanced  discs  and  a  pinion;  the  latter  engages  with 
the  gear  of  the  hoisting  drum  shaft.  This  drum  is  provided  with 
housings  at  both  ends,  one  for  the  hoisting  band  and  the  other 
for  the  brake  band;  also  with  bronze  bushings  for  loose  mounting 
on  the  drum  shaft.  To  engage  the  hoisting  drum,  the  hoisting 
friction  is  tightened  by  a  small  steam  ram.  An  older  method, 
used  to  drive  the  drum,  was  by  positive  gearing,  but  this  was 
slower,  less  reliable  under  severe  strain  and  operated  less  smoothly 
than  the  friction  clutch. 

The  heavy  hand-forged  hoisting  chain  usually  passes  from  the 
hoisting  drum  to  the  fair  lead,  or  sheaves,  below  the  swing  circle, 
thence  over  the  lower  boom  sheave,  and  along  the  boom  to  the 
upper  boom  sheave,  thence  over  one  of  the  boom  point  sheaves 
and  around  the  dipper  sheave  block,  returning  to  and  around 
the  second  boom  point  sheave  and  back  to  the  dipper  sheave 
block  becket  where  it  is  fastened.  By  this  means  the  second, 
or  hoisting  motion,  is  accomplished. 

To  check  the  empty  dipper  when  lowering,  the  band  brake, 
operated  by  a  foot  lever,  is  used.  Both  the  hoisting  friction 
and  check-bands  are  lined  with  asbestos  or  wood  blocks. 

The  hoisting  engine  is  also  used  to  propel  the  shovel.  This  is 
accomplished  by  a  propelling  shaft  driven  by  gearing  from  the 
hoisting  drum-shaft.  A  jaw  clutch  engages  the  propelling  shaft 
with  the  double  pocket-sheave  which  is  loosely  mounted  thereon. 
From  the  double  pocket-sheave  steel  chains  lead  to  sheaves  on 
the  two  inner  axles  of  the  trucks,  and,  if  desired,  traction  may  be 
had  from  all  eight  wheels  by  providing  additional  sheaves  and 
chains  to  connect  the  outer  with  the  inner  axles.  By  using 
square  axles  and  split  pocket-sheaves  with  square  centres,  the 
sheave  halves  may  be  bolted  together  so  as  to  permit  them  to 
travel  across  the  axle,  need  no  keying,  and  yet  be  very  secure. 

The  swinging  engine  is  usually  like  the  crowding  engine  except 
for  the  crank  shaft  and  reverse  valve.  It  drives  the  swinging- 
drum  through  an  intermediate  shaft.  From  the  swinging-drum 
the  two  ends  of  the  swinging  chain,  or  cable,  are  passed  across  two 
sheaves,  located  at  the  front  end  of  the  car,  and  then  around  the 
swinging-circle  and  attached  to  the  foot  of  the  boom  or  to  the 
circle.  By  rotating  the  swinging-drum  in  the  proper  direction, 


12  STEAM  SHOVEL  MINING 

the  swinging-circle  and  boom  are  caused  to  swing  in  the  direction 
desired,  and  thus  the  third  motion  of  the  shovel  is  accomplished. 

The  hoisting  and  swinging  engines  are  controlled  by  throttles 
operated  by  the  shovel  runner,  but  the  crowding  engine  is  con- 
trolled by  the  craneman,  who  also  trips  the  dipper. 

Boiler. — This  is  located  over  the  rear  trucks  and  generates 
steam  for  the  engines.  On  the  larger  shovels  the  locomotive 
type  is  generally  used,  but  on  small  shovels,  the  less  economical 
vertical  submerged  tube  type  prevails.  Attention  should  be 
given  to  provide  boilers  of  ample  capacity  and  good  steaming 
qualities.  Under-capacity  causes  surging  in  the  boiler  and 
drawing  over  of  water  into  the  engines.  A  working  pressure  of 
125  Ibs.  per  sq.  in.,  is  usual  but  they  are  tested  to  much  higher 
pressures  for  safety.  Lagging  the  boiler  and  pipes  results  in 
fuel  economy  and  drier  steam  at  the  engines.  Some  fire  boxes 
are  equipped  with  shaking  grates.  All  boilers  should  be  provided 
with  accurate  pressure  gauges,  safety  valves,  duplex  steam  feed- 
pumps, injectors  and  whistles.  Water  tanks,  holding  about 
1500  gallons,  are  placed  on  one  or  both  sides  of  the  boiler,  and  a 
rear  platform  carries  a  small  amount  of  coal. 

All  of  the  machinery,  except  that  exposed  on  the  front  end, 
is  protected  by  the  housing.  The  rear  door  swings  upward  to 
form  a  roof  over  the  rear  platform.  A  short  bench,  and  vice  and 
lockers  are  found  convenient. 

Shipping. — To  ship  a  shovel  across  the  country  by  rail  the 
boom  and  dipper  with  handle  are  loaded  on  a  flat  car,  and  the 
A-frame  back  leg  is  adjusted  to  lower  the  A-frame  top  to  clear 
at  a  height  of  about  14  ft.  above  the  rail. 

Modern  Standard  Construction. — Like  most  other  mechanical 
inventions,  the  first  steam-shovels  were  small  and  crude  in  design, 
and  mechanically  far  from  perfect.  Constant  study,  usage  and 
experiment,  however,  have  resulted  in  wonderfully  good  design, 
and  enormously  increased  size  and  strength  with  corresponding 
capacity.  Contemporaneous  with  the  development  of  the  shovel 
has  been  the  perfecting  of  various  materials  of  construction 
entering  into  their  manufacture.  Among  these  are  manganese- 
steels,  generously  used  for  such  items  as  shipper-shaft  pinions 
and  racks,  dipper  fronts  or  entire  dippers,  dipper  teeth  and  other 
parts  subject  to  great  abrasive  wear;  basic  open-hearth  cast 
steel  and  f orgings  instead  of  cast  iron ;  rigid  castings  in  place  of 
structural  steel  for  jack  arms,  swing  circles  and  front  ends; 


THE  POWER  SHOVEL  13 

and  steel  in  place  of  wood  for  such  items  as  the  car  frames  and- 
trucks.  Most  of  the  materials  are  carefully  tested  in  the  test- 
ing laboratory  and  must  fulfill  rigid  requirements.  The  actual 
working  up  and  balance  of  the  material  into  the  various  members 
has  been  another  contemporary  improvement  of  great  importance 
and  is  seen  in  the  machin^cut  or  ground  gears,  the  hammered 
steel  shafting,  the  carefuw  forged  chains,  and  the  construction 
of  boilers  and  other  D^^T  with  a  view  to  fuel  economy.  Much 
attention  has  beensij^.  to  the  scientific  lubrication  of  all  bear- 
ing surfaces,  both  as  to  the  lubricant  used  and  its  positive  but 
economical  application.  A  point  of  great  convenience  in  opera- 
tion and  of  economy  and  accuracy  in  manufacture,  is  the  inter- 
changeability  of  spare  parts.  With  the  best  of  design  many 
shovel  parts  are  subject  to  breakage  and  wear  so  that  provision 
must  be  made  to  replace  them  as  quickly  and  as  economically 
as  possible.  This  is  done  by  carrying  in  stock  the  interchange- 
able spare  parts  which  are  likely  to  be  required  and  thus  avoiding 
serious  delays  in  keeping  the  shovels  working. 

In  design,  the  required  strength  of  the  members  is  calculated 
as  accurately  as  possible,  but  working  conditions  are  so  variable 
that  actual  usage  in  the  field  and  under  the  severest  conditions 
is  considered  the  best  criterion  as  a  guide  to  the  design  of  many 
parts.  The  engines,  however,  are  subject  to  fewer  unknown 
strains  and  may  be  designed  with  considerable  precisian.  In 
this  respect  it  is  the  aim  of  certain  builders,  such  as  the  Marion, 
to  design  their  engines  to  have  sufficient  power  to  work  well 
under  all  normal  loading,  but  in  the  event  of  great  overload  to 
have  them  stall  rather  than  risk  breaking  some  member  of  the 
shovel.  Other  builders,  such  as  the  Bucyrus,  design  their 
engines  more  powerfully,  depending  on  the  shovel  runner  to  use 
reasonable  care  and  judgment  in  operating.  In  the  hands  of 
competent  and  experienced  runners,  the  higher  powered  machines 
are  credited  with  somewhat  greater  capacity  than  those  of  lower 
power,  but  where  operated  by  inexperienced  or  careless  runners, 
the  latter  class  will  be  broken  down  less  frequently  and  over  a 
given  period  may  show  an  equal  or  greater  task  performed  than 
the  former.  Both  classes  appear  to  be  held  in  about  equal  es- 
teem by  the  users.  The  design  of  the  boilers  provides  for  ample 
steaming  capacity,  fuel  economy,  and  thorough  testing  for  safety. 
For  the  heavier  shovels  the  locomotive  type  is  best  but  for  light 
shovels  vertical  boilers  are  still  general.  The  use  of  an  outer 


14  STEAM  SHOVEL  MINING 

shell,  as  in  the  Parker  construction,  provides  an  annular  spaoe 
for  heating  the  feed  water  to  a  point  where  most  of  the  scale- 
forming  impurities  are  deposited.  These  solids  may  readily 
be  removed  from  the  outer  ring,  and  the  formation  of  scale  in 
the  boiler  proper  is  greatly  retarded,  thus  making  for  steaming 
efficiency  and  less  frequent  washing  out.  Longer  usage  will 
show  to  what  extent  these  advantages  apply.  The  use  of  pure 
water  in  the  boilers  is  of  great  importance,  regardless  of  the 
design. 

Thus  after  more  than  fifty  years  of  usage  and  study,  the  engi- 
neers and  builders  of  modern  shovels  have  settled  on  designs 
and  materials  of  construction  which  may  be  called  standard, 
meaning  that  they  embody  those  characteristics  which  have 
proven  best  in  practice.  As  the  work  thrown  on  them  in  hard 
digging  is  probably  more  severe  than  that  done  by  any  other  class 
of  excavator,  and  as  their  use  is  broader  and  the  operating  con- 
ditions more  varied,  their  evolution  will  no  doubt  continue,  but 
the  present  modern  shovel  must  be  considered  as  an  eminently 
satisfactory  machine.  The  general  tendency  in  designs  is  con- 
stantly towards  machines  of  larger  size  and  capacity. 

The  Railroad,  or  Standard  Type. — The  type  of  machine  illus- 
trated by  Fig.  3,  is  that  generally  employed  for  railroad  and  con- 
struction work,  for  stripping  and  mining  large  deposits  of  low 
grade  ores,  and  for  excavating  canals  and  similar  work.  They 
are  [usually  designed  with  railroad  trucks  for  operating  from  a 
railroad  track,  but  they  may  be  equipped  with  broad  traction 
wheels  for  operating  in  places  where  a  track  would  not  be 
desirable.  The  usual  range  in  weight  is  from  25  tons  to  135 
tons  and  the  capacity  of  the  dipper  ranges  from  one-half  cubic 
yard  to  8  cubic  yards.  The  boom  swings  through  a  horizontal 
arc  of  from  a  little  more  than  a  half  circle  up  to  about  260°. 
The  general  description  given  on  pages  6  to  12  is  of  this 
type. 

The  lighter  sizes  are  used  in  brick  yards,  gravel  pits,  and  in 
some  instances  in  tunnels.  They  may  be  expected  to  load  from 
30  to  90  cu.  yd.  per  hour.  Those  weighing  about  40  tons  and 
equipped  with  lj^-cu.  yd.  dippers  are  common  on  general  con 
tract  work,  on  narrow  cuts,  and  are  occasionally  used  in  tunnels 
of  large  size.  They  will  load  from  60  to  180  cu.  yd.  per  hour. 
The  70-ton  shovel  is  used  on  railroad  work  and  the  heaveir 
classes  of  construction.  With  a  2-cu.  yd.  dipper  it  will  load  from 


THE  POWER  SHOVEL 


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16 


STEAM  SHOVEL  MINING 


80  to  240  cu.  yd.  per  hour.  The  80-ton  size  carrying  a 
yd.  dipper  is  used  for  the  same  class  of  work — but  has  a  some- 
what greater  capacity.  The  90-ton  size  with  a  3^-  or  ty^-cu. 
yd.  dipper  will  load  from  120  to  350  cu.  yd.  per  hour  and  is  much 
used  in  large  open-pit  mines,  and  large  cuts.  The  100-ton  shovel 
is  used  on  hard  and  heavy  work  similar  to  the  90-ton  machine, 
but  will  handle  a  4-cu.  yd.  dipper  and  load  more  material. 
Shovels  of  great  power  weighing  120  to  135  tons  are  built  and 


TABLE  2. — WORKING  DIMENSIONS  OF  RAILROAD  TYPE  SHOVELS 


Chain  type  shovels 

Wire  rope 
Shovels 

110  C 

100  C 

88  C 

70  C 

68  C 

40RorC 

Class 
80 

Class 
45 

A 
B 

Dumping  radius.  . 

-32' 

29' 

30'  3" 

27' 

26'  5" 

21'  6" 

33' 

27' 

Height  of  dump.  .  . 

17' 

17' 

18' 

16'  6" 

16' 

12' 

18'  6" 

16'  6" 

D 

Depth  of  cut, 
shovel    track    to 
loading  track  .... 

10' 

10' 

9'  6" 

9'  6" 

9' 

5' 

11'  6" 

9'  6" 

Max.    depth      of 
thorough  cut  

16' 

15'  6" 

15' 

14' 

13' 

7'  9" 

16'  6" 

13'  6" 

].• 
P 

Q 

B 

Digging  radiusat 
8'  elevation  

33' 

33' 

33'     \Y2" 

30' 

28'  4" 

23' 

32' 

26' 

Spread  of     jack 
screws  

22' 

20' 

20' 

18'  4" 

18' 

15' 

19' 

18' 

Height  of  boom.  . 

33' 

28'  9" 

28'  11K" 

27'  OH" 

26'  7" 

21'  3H" 

33' 

27'  7" 

Depth  of  cut  be- 
low rail 

6' 

5'  6" 

5'    6" 

4'  6" 

4' 

2'  9" 

5' 

4' 

THE  POWER  SHOVEL  17 

are  suitable  for  the  heaviest  service  in  hard  digging.  They  have 
a  capacity  of  250  to  400  cu.  yd.  per  hour.  The  capacities  given 
here  are  merely  approximate,  as  there  are  may  factors  to  be 
considered  later,  that  affect  or  control  what  the  machines  should 
be  expected  to  do.  Because  of  operating  delays  it  will  be  safer 
to  use  the  lower  capacities  in  calculating  what  may  be  expected 
of  a  given  shovel  over  a  considerable  period  of  operation. 

Table  1  gives  the  general  dimensions,  and  Table  2  gives  the 
working  dimensions  of  this  type  of  steam-shovel.  A  column  is 
also  included  showing  these  characteristics  for  the  wire  rope 
shovels. 

The  Revolving  Type. — This  type  of  shovel  is  designed  to  work 
in  a  full  circle,  turning  in  either  direction,  and  operating  in  a 
manner  similar  to  that  of  a  steam-crane.  The  lighter  sizes  range 
from  about  17  to  55  tons,  are  equipped  with  dippers  of  from  %  to 
1%  cu.  yd.,  and  will  excavate  from  25  to  100  cu.  yd.  per  hour. 
Fig.  6  is  a  line  drawing  of  one  of  the  larger  shovels  built  by  the 
Marion  Co.  They  are  mounted  either  on  trucks  or  traction 
wheels.  Only  one  man  is  required  to  operate  many  of  them,  but 
a  lower  output  must  then  be  expected.  These  machines  find 
their  greatest  use  in  street  construction,  basement  and  trench 
excavation,  and  in  gravel  and  clay  beds.  Because  they  dig  and 
then  deliver  material  at  any  angle  from  the  digging  face,  they 
often  eliminate  a  loading  operation.  They  are  also  useful  when 
equipped  with  a  clam-shell  or  an  orange-peel  bucket  instead  of 
the  usual  dipper.  This  change  is  made  by  changing  booms. 

A  class  of  very  large  revolving  shovels  is  made  and  used  for 
stripping  overburden  from  beds  of  coal,  iron  ore  and  similar 
deposits.  These  shovels  (Fig.  6)  have  been  highly  developed  and 
are  the  heaviest  and  of  the  greatest  capacity  of  any  built.  They 
have  a  working  weight  of  from  95  tons  to  325  tons,  carry  dippers 
of  from  1J^  to  8  cu.  yd.,  use  booms  from  45  to  90  ft.  long,  and 
dipper  handles  from  54  to  60  ft.  long.  To  support  them  two 
tracks  of  3  ft.  gauge  are  generally  employed,  though  they  may  be 
mounted  on  rollers,  or  caterpillar  tractors.  To  equalize  the 
frame  stresses  and  give  the  flexibility  of.  a  three  point  suspension, 
a  hydraulic  truck  equalizing  device  is  used  on  each  corner  of 
the  truck  frame.  They  will  build  dumps  as  high  as  65  ft.,  have 
a  radius  of  cut  at  grade  of  from  34  ft.  to  70  ft.,  and  at  40  ft.  ele- 
vation have  a  maximum  radius  of  101  ft.  They  will  handle 

from  150  to  300  cu.  yd.  (place  measure)  per  hour, 
*   2 


18 


STEAM  SHOVEL  MINING 


THE  POWER  SHOVEL 


19 


Equipped  with  long  booms,  they  are  able  to  strip  wide  cuts, 
dumping  the  excavated  material  at  a  sufficient  height  and  dis- 
tance to  permit  mining  of  the  uncovered  material  without  further 
handling  of  the  overburden.  With  no  loading  or  transporting 
of  stripping  required,  this  method  effects  a  great  saving  in  cost 
where  conditions  are  favorable  to  its  application.  Once  the 
overburden  is  removed,  the  underlying  mineral  deposit  may  be 
mined  in  any  manner  desired,  following  along  in  the  wake  of 
the  stripping  shovel.  Besides  having  a  great  working  range  of 
depth  and  width  of  face,  they  leave  the  mineral  deposit  in  good 
shape  to  obtain  a  clean  and  high  recovery  and  at  minimum  cost. 

They  are  also  suitable  for  excavating  big  railroad  cuts  and  large 
canals,  where  the  material  must  be  removed  in  cars  and  under 
conditions  unfavorable  for  the  use  of  dray-line  excavators. 

TABLE  3. — TABLE  OF  DIMENSIONS — SMALL  REVOLVING  SHOVELS 


n 

14-B 

18-B 

25-B 

35-B 

Effective  pull  on  dipper,  Ib  

12300 

18250 

25800 

31490 

Capacity  of  dipper  

^3  cu.  yd. 

%  cu.  yd. 

l34  cu.  yd. 

1%  cu.  yd. 

fMain  

5"  X  6" 

6    "  X  7" 

7"  X  8" 

8"  X  8" 

Size  of  engines  \  Thrust  

4"  X  5" 

4%"  X  5" 

5"  X  6" 

6"  X  6" 

[  Swing  

4"  X  5" 

4%"  X  5" 

5"  X  6" 

6"  X  6" 

Revolving  frame  f  Length  

15'  3" 

16'  0" 

17'  9" 

19'  4" 

(over-all  house      1  Width  ....  

9'0" 

10'  0" 

10'  0" 

10'  0" 

dimensions) 

Wheel  base  f  Traction 

7'  3" 

8'  0" 

8'  9" 

10'  3" 

1  Truck  

7'  3"    ' 

8'0" 

8'  9" 

10'  3" 

Width  over  traction  wheels  

8'  6" 

9'  6" 

11'  834" 

12'  4" 

Vertical 

Boiler  f  Type  

Vertical 

Vertical 

Submerged 

Loco. 

1  Dimensions  

12"  X  7'  8%" 

48"  X  7'  812" 

54"  X  8'  11" 

48"  X  9'  7" 

Water  tank,  total  capacity  

275  gals. 

350  gals. 

400  gals. 

500  gals. 

Weight  in  working      Railroad  

20      tons 

25      tons 

33  %  tons 

42^  tons 

order                            Traction  

21       tons 

27      tons 

37  M  tons 

46%  tons 

Caterpillar  . 

26^  tons 

30M  tons 

44  1^  tons 

50%  tons 

f  Railroad  

17%  tons 

22      tons 

30  %  tons 

38        tons 

Shipping  weight  <  Traction  

19       tons 

24      tons 

33*4  tons 

42  }i  tons 

(Caterpillar  

24      tons 

27}$  tons' 

40  3  £  tons 

46  }£  tons 

Approx.  gross  weight     Railroad.  . 

18%  tons* 

23%  tons 

32^  tons 

41        tons 

boxed  for  export           Traction.. 

20%*-  'tons* 

26  %  "tons 

36        tons 

46       tons 

(1  ton—  2000  Ib.)          Caterpil'ai 

26       tons 

31      tons 

42^  tons 

51        tons 

Approx.  volume     Railraod  

1300  cu.  ft. 

1750  cu.  ft. 

2350  cu.  ft. 

3000  cu.  ft. 

for  export              Traction  

1400  cu.  ft, 

1950  cu.  ft. 

2750  cu.  ft. 

3500  cu.  ft. 

Caterpillnr.  .  .  . 

1800  cu.  ft. 

2400  cu.  ft. 

3250  cu.  ft. 

3800  cu.  ft. 

20 


STEAM  SHOVEL  MINING 


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THE  POWER  SHOVEL 


21 


TABLE  5. — TABLE  OP  DIMENSIONS — LARGE  REVOLVING  SHOVELS 


150-B 

175-B 

225-B 

Effective  pull  on  dipper,  pounds 
Capacity  of  dipper  

43000 
2U  yd. 

60000 
3K  yd. 

77500 
6yd. 

Length  of  boom  

60' 

75' 

80' 

Length  of  dipper  handle  
Length  of  revolving  frame  
Width  over  sub-base. 

38' 
37'  3" 
22' 

48' 
40'  5^" 

28'  2" 

58' 
48'  8" 
33'  8' 

Distance  C  to  C  of  trucks  

20'  X  17' 

24'  X  24' 

30'  X  30' 

Locomotive  boiler  

58"  X  15' 

64"   X  15'  10" 

76"  X  18' 

Water  tank  capacity,  gallons  .... 
Main  engines,  double 

1460 
10"  X  12" 

2500 
12"  X  15" 

3000 
14"  X  16" 

Swing  engines,  double 

8"  X  8" 

9"  X  9" 

10"  X  10" 

Thrust  engines,  double     

7>£"  X  7" 

&A"  X  8" 

10"  X  10" 

Approx.  net  shipping  weight, 
pounds  .  .  . 

248  000 

363,000 

521,000 

Approx.  working  weight,  pounds 

316,000 

428,000 

624,000 

22 


STEAM  SHOVEL  MINING 


TABLE  6. — WORKING  DIMENSIONS  OF  LARGE  REVOLVING  SHOVELS 


225^B 

175-B 

150-B 

Pitch  of  boom                           ...      

45° 

45° 

45° 

A      Dumping  radius 

94'-6" 

85'-0" 

74'-0" 

B      Height  of  dump  (dipper  door  open)  
Q     Level  floor  radius              

61'-0" 
59'-0" 

52'-0" 
56'-0" 

40'-0" 
46'-0" 

D     Center  to  center  of  tracks 

30'-0" 

24'-0" 

17'-0" 

E      Radius  of  boom  

77'-0" 

68'-0" 

56'-0" 

F      Height  of  boom               .          

76'-0" 

66'-0" 

53'-0" 

G      Digging  radius  at  8'  elevation  
H     Height  of  cut   

88'-0" 
72'-0" 

78'-0" 
61'-0" 

68'-0" 
47/-0" 

I      Radius  of  rear  end  

32'-4" 

29'-0" 

27'-0'/ 

An  ordinary  railroad  type  shovel  would  often  require  8  or  9 
cuts,  with  all  the  attendant  changes  of  position  of  the  loading 
track,  to  make  an  excavation  that  one  of  these  great  revolving 
shovels  could  make  in  one  large  cut. 

Table  3  gives  the  dimensions,   and  Table  4  the  working 
dimensions  of  the  small  Bucyrus  revolving  shovels. 

Table  5  gives  the  dimensions,  and  Table  6  the  working  dimen- 
sions of  the  large  Bucyrus  shovels. 

Table  7  gives  the  dimensions  of  some  medimum-sized  Marion 
shovels. 


THE  POWER  SHOVEL 


23 


TABLE  7. — SPECIFICATIONS  OF  MARION  COAL  STRIPPING  STEAM  SHOVELS 


Ys  TO  1  SLOPE  OF  SPOIL  BANK 
MODI!L  211 

2- YARD  DIPPER,  45-FooT  BOOM 
A       C       C'        D         E          F 


Y±  TO  1  SLOPE  OF  SPOIL  BANK 

MODEL  211 
2- YARD  DIPPER,  45-FooT  BOOM 

A       C       C'        D         E          F 


14'     29'      29'      17'          4'  13' 

16'     29'      29'      16'          4'  12' 

18'     20'      20'      16'          4'  12' 

20'      11'      11'      25'    '    13'  12' 

MODEL  231 
3^- YARD  DIPPER,  55-FooT  BOOM 

A       C       C'        D         E  F 


12'      29'      29'      17'          4'  13' 

14'      29'      29'      16'          4'  12' 

16'      20'      20'      16'          4'  12' 

18'      12'      12'      24'        12'  12' 

MODEL  231 

3*4 -YARD  DIPPER,  55-FooT  BOOM 

A       C       C'        D         E  F 


20'  36'      36'  19' 

22'  36'      36'  18' 

24'  27'      27'  18' 

26'  II'I 


4'  15'. 
4'  14' 
4'  14' 


18'  36'  36'  19'  4'  15' 

20'  32'  32'  18'  4'  14' 

22'  22'  22'  18'  4'  14' 

24'  14'  14'  27'  13'  14' 


Extra  Long  Booms  and  Dipper  Sticks. — To  meet  special  or 
unusual  requirements,  the  leading  shovel  builders  are  generally 
willing  to  recommend  or  design  machines  considered  best  suited 
to  the  conditions. 

Some  requirements  are  best  filled  by  machines  of  standard 
design,  but  equipped  with  extra  long  booms  and  dipper-handles, 
and  braced  with  special  wide  spread  jack-arms.  In  brick 
manufacture,  where  a  uniform  mixture  of  material  is  desired 
mined  directly  from  bottom  to  top  of  the  working  bank,  such  a 
shovel  permits  of  very  high  continuous  cuts.  Again  in  digging 
canals  and  aqueducts,  an  extremely  high  lift  is  often  desired, 
so  that  the  excavated  material  may  be  loaded  into  cars  on  the 
bank  or  cast  directly  on  the  banks.  By  decreasing  the  size 


24  STEAM  SHOVEL  MINING 

of  the  dipper  and  increasing  the  length  of  the  boom  and  dipper 
stick  such  lifts  may  be  effected.  For  digging  to  depths  of  from 
10  to  30  feet  below  grade,  one  of  these  shovels  may  have  its 
car-frame  mounted  on  transverse  sills,  which  are  in  turn  mounted 
on  trucks  or  rollers  equipped  to  run  parallel  to  and  on  both  sides 
of  the  canal  being  excavated.  The  long  booms  and  dipper  sticks 
also  permit,  when  desirable,  the  dumping  of  material  at  a  con- 
siderable distance  to  the  sides  of  the  excavation.  In  practical 
working,  it  is  usually  undesirable  to  plan  banks  of  a  height  much 
greater  than  the  width  that  a  given  shovel  may  be  expected  to 
cut;  this  width  being  measured  from  the  loading  track  to  a 
point  on  the  bank  about  6  ft.  above  grade.  Thus  the  length  of 
boom  and  dipper  stick  should  bear  a  direct  relationship  to  the 
height  of  bank  desired. 

Quarry,  Tunnel  and  Stope  Shovels. — A  light  weight  type  of 
shovel  is  often  used  for  loading  rock  broken  in  advancing  tunnels 
or  adits,  in  quarries  or  even  in  certain  underground  stopes. 
Shovels  for  such  uses  are  made  by  the  Bucyrus,  Marion,  Ball, 
and  Thew  Companies. 

The  Thew,1  as  illustrated  by  Fig.  7,  has  several  unique 
features.  It  is  a  self  contained  machine,  having  the  upright 
tubular  boiler,  boom,  engine,  small  coal  bunker  and  water  tank 
all  placed  on  a  revolving  platform.  The  earlier  steam-driven 
machines  and  the  present  electric  and  gasoline  ones  are  operated 
by  one  engine.  On  the  steam  machines  this  engine  is  of  the 
double  reversing  type,  runs  continuously,  and  is  controlled  by  a 
fly-ball  governor.  The  later  steam  machines  have  independent 
engines  for  hoisting,  swinging  and  crowding  and  have  the  usual 
control  levers  and  throttles.  One  of  the  unique  features  is  the 
horizontal  crowding  motion  having  a  movement  of  about  eight 
feet.  This  is  accomplished  by  suspending  the  dipper  by  an 
adjustable  arm  hinged  to  a  sort  of  trolley  or  carriage  and  arranged 
to  move  horizontally  along  a  trackway  and  thus  parallel  to  the 
grade.  This  permits  broken  material  to  be  shovelled  clean 
along  a  flat  bottom  for  8  or  10  ft.  Another  feature  is  that  the 
dipper  handle  is  built  with  a  swivel  clamp  designed  to  permit 

1  Manufactured  by  the  Thew  Automatic  Shovel  Co.,  Lorain,  Ohio.  They 
are  used  in  clay  and  shale  working  industries;  underground  by  the  American 
Zinc  Lead  &  Smelting  Co.  of  Joplin,  Mo.,  in  the  ore  quarries  of  the  Granby 
Company,  of  Phoenix,  B.C.,  and  elsewhere.  Over  1200  are  rated  in  use 
on  such  work.  The  makers  claim  this  shovel  to  be  the  pioneer  of  the  full- 
circle  swing  type. 


THE  POWER  SHOVEL 


25 


the  dipper  to  turn  or  swivel  when  working  its  way  through 
obstructions,  thus  avoiding  concentrated  strains.  They  are 
self-propelling  and  built  to  run  on  traction  wheels  or  track, 
using  jacks  in  the  latter  case.  They  carry  dippers  of  from  %  to 
1/4  cu.  yd.  and  handle  from  25  to  40  cu.  yd.  of  clay  or  shale  per 
hour  with  a  single  operator,  or  from  40  to  60  cu.  yd.  with  the 
addition  of  a  fireman.  One  or  two  trackmen  are  usually  pro- 
vided. 

The  Bucyrus  27-D  Coal-loader  is  an  excavator  which  has  found 
much  favor  in  digging  and  loading  coal  from  the  thin  flat  beds 
of  Kansas.  These  beds  are  previously  uncovered  by  large 


>NS  -THEW  SHOVELS  -REV 

1 1IET1THTIZ 


•'.  TO  HE0  C0',r 

T 


FIG.  7. — Standard  Thew  shovel. 

revolving  shovels.  Usually  the  beds  are  cut  up  by  seams  and 
layers  of  fire-clay  or  shale,  locally  called  "horsebacks,"  which 
must  be  kept  out  of  the  coal  and  amount  to  about  10  or  15  per 
cent,  of  the  cut.  The  machine  is  well  suited  to  this  work.  It 
has  three  motions  similar  to  all  shovels,  but  the  crowding  motion 
is  kept  in  a  straight  line  and  may  be  held  at  any  acute  angle 
with  the  horizontal.  The  dipper  may  thus  cut  a  level  floor 
lifting  the  coal  bed  cleanly  off  its  bottom  but  stopping  at  any 
seam,  just  about  the  same  way  that  a  man  would  operate  a 
scoop  on  a  shovelling  floor.  Having  the  dipper  loaded,  the 
boom  is  hoisted,  and  the  machine  is  rotated  to  the  desired 


26 


STEAM  SHOVEL  MINING 


dumping  point  where  the  dipper  is  tripped  and  discharges 
forward.  The  maximum  radius  is  30  ft.  6  in.  Fig.  8  gives  an 
idea  of  the  appearance  and  construction  of  these  loaders.  They 
have  a  capacity  of  from  40  to  70  tons  per  hour  in  coal  beds  from 
2  to  4  ft.  thick.  The  machine  is  capable  of  making  a  complete 
cycle  in  30  sec.  The  price  of  this  machine  mounted  on  cater- 
pillar tractor  was  about  $14,000  at  factory  in  1916.  Its  shipping 
weight  is  30  tons  and  working  weight  33  tons. 

The  Erie1  shovel  is  a  recent  one  having  a  unique  crowding 
device  which  automatically  permits  the  operator  to  cut  a  level 


FIG.  8. — Bucyrus  27-D  coal  loader. 

floor  or  a  floor  of  a  determined  slope.  This  is  useful  on  road  and 
ditch  work.  A  device  is  fitted  to  the  ordinary  crowding  mechan- 
ism by  means  of  which  the  crowding  engine  may  be  made  to 
work  automatically  in  definite  relationship  to  the  hoisting 
motion  without  having  the  operator  constantly  playing  one 
motion  against  the  other.  This  device  simply  consists  of  a 
small  pinion,  fitted  to  one  end  of  the  shipper  shaft,  which  operates 
a  small  auxiliary  rack  traveling  in  and  out  with  the  dipper 
stock.  On  the  end  of  the  rack  is  a  small  roller  traveling  on  a 
track  which  represents  the  desired  bottom  to  be  cut.  This 
1  The  Erie  Shovel  is  built  by  the  Ball  Engine  Co.,  of  Erie;  Penn. 


THE  POWER  SHOVEL  27 

mechanism  is  connected  to  the  control  valves  governing  the 
crowding  and  hoisting  engines  and  thus  controls  their  relative 
movement.  By  setting  the  roller  track  in  the  correct  position 
the  desired  grade  of  bottom  will  be  cut.  If  desired  the  device 
may  be  thrown  out  of  use  and  the  shovel  operated  in  the  usual 
way. 

This  shovel  weighs  20  tons,  carries  a  17^-ft.  boom  and  a 
34-cu.  yd.  dipper,  cuts  a  maximum  floor  width  of  35  ft.,  is  fitted 
with  either  traction  wheels  or  rail  trucks  and  is  of  the  revolving 
type. 

The  conditions  must  be  exceptional  for  the  economic  operation 
of  these  light  shovels  underground  but  under  quite  favorable 
conditions  both  the  loading  time  and  cost  may  be  materially 
reduced  as  compared  with  hand-loading.  The  stope  or  chamber 
in  which  they  are  to  be  used  must  be  at  least  18  ft.  high  and  30 
ft.  in  diameter  and  even  then  the  machines  are  awkward  io 
move  around  as  the  piles  of  ore  are  depleted.  Coarse  material 
must  be  broken  as  encountered  to  facilitate  loading  and  con- 
siderable will  usually  be  left  scattered  around  which  must  be 
loaded  by  hand.  Because  of  the  disadvantages,  the  cost  of 
mechanical  shovel-loading  underground  may  easily  exceed 
that  of  hand-loading. 

Before  leaving  these  light  tunnelling  and  loading  machines, 
it  may  be  mentioned  that  several  so-called  "  shovelling 
machines' n  have  been  designed  and  put  on  the  market  for  such 
purposes  as  shovelling  and  loading  the  broken  material  in  tunnel 
advances,  in  stopes  and  from  stock  piles.  Here- again  conditions 
must  be  favorable  for  their  use  if  they  are  to  show  a  lower  cost 
than  hand  work,  though  more  often  some  saving  in  time  may  be 
effected.  They  are  subject  to  hard  usage  and  it  has  been  found 
that  the  expense  and  delay  in  keeping  them  in  operation  is  often 
a  serious  drawback.  Portable  loaders,  which  simply  elevate 
rock  by  means  of  a  conveyor  belt,  but  do  not  "shovel,"  have  been 
used  in  drifts  with  good  results.2 

Wire-Rope  Shovels. — A  steam-shovel  of  later  design  and 
known  as  the  Robinson  or  Atlantic  type,  was  developed  by  the 
American  Locomotive  Company  and  after  trials  covering  1908 
and  1909,  was  put  out  by  the  American  Equipment  Company 

1  Among  these  are  the  Myers- Whaley,  made  at  Knoxville,  Term.,  and  the 
Halby,  made  by  the  Lake  Shore  Engine  Works,  at  Marquette,  Mich. 

2  P.L.S.M.I.  Sept.  6-9,  1915,  Morris-Lloyd  Mine. 


28  STEAM  SHOVEL  MINING 

in  1910  in  the  iron  ore  service  of  the  Lake  Superior  iron  ranges. 
It  is  now  built  by  the  Bucyrus  Company,  as  illustrated  by  Fig. 
9;  Tables  1  and  2  give  its  characteristics. 

This  shovel  is  designed  to  do  the  same  class  of  work  as  the 
heavier  standard  shovels;  it  has  the  distinctive  feature  of  using 
a  direct  wire-rope  hoist  instead  of  the  differential  chain  and  pulley 
hoist.  The  hoisting  engine  is  bolted  to  the  base  of  the  boom 
and  the  wire  rope  passes  from  the  drum  over  one  large  twin 
grooved  sheave  directly  to  the  dipper  back.  The  hoisting 
drum  is  of  large  diameter  and  is  driven  by  two  machine-cut 
gears.  The  steel  hoisting  rope  is  made  up  of  two  parallel  cables 
equalizing  their  load  by  passing  around  a  thimble  on  the  dipper. 
The  placing  of  the  hoisting  engine  at  the  end  of  the  boom  makes 
more  room  available  in  the  body,  part  of  whjch  is  used  to  house 
the  extra  large,  efficient,  locomotive-type  boiler  with  its  large 
water  tank.  This  arrangement,  however,  throws  considerable 
additional  weight  on  the  front  end  and  turntable. 

The  Class  80  Atlantic  shovel  has  a  working  speed  of  3  to  5 
dippers  per  minute.     Bunker  capacity  is  8800  Ib. 

In  addition  to  this  heavy  shovel,  others  are  built  designed  to 
use  dippers  as  small  as  1  cu.  yd.  capacity. 

The  design,  materials  and  workmanship  are  of  a  high  class, 
and  among  the  advantages  claimed  for  the  shovel  are  increased 
efficiency  due  to  the  elimination  of  the  friction  of  the  chain  links 
passing  over  their  several  sheaves,  lower  coal  consumption 
due  to  the  use  of  a  boiler  of  large  steam  capacity,  the  ability  of 
the  dipper  to  take  large  boulders  and  full  loads  and  its  sim- 
plicity due  to  the  elimination  of  the  bail  and  the  increased  speed 
and  ease  of  the  manoeuvres  making  faster  loading.  In  severe 
service  it  was  found  that  the  earlier  designs  were  not  strong 
enough,  so  that  when  competing  with  the  chain-type  of  shovel, 
the  delays  due  to  breakdowns  were  a  serious  disadvantage. 
By  strengthening  the  shovel  to  the  ruggedness  of  the  chain- 
type,  its  advantages  of  design,  fuel  economy,  extra  lift,  ease 
of  operation  and  increased  loading  speed  when  working  in 
favorable  ground,  recommend  it  to  favorable  attention. 

It  may  be  mentioned  that  just  prior  to  1906  the  Allis-Chalmers 
Company  of  Milwaukee  brought  out  a  wire-rope  shovel.  This  had 
some  unique  features  including  a  scheme  to  relieve  the  weight 
on  the  boom  and  turntable  by  so  leading  the  ropes  that  the 
working  strains  are  resolved  into  a  lifting  component,  made 


THE  POWER  SHOVEL 


29 


30  STEAM  SHOVEL  MINING 

effective  at  the  foot  of  the  boom,  thus  lessening  the  load  on  the 
turntable  and  reducing  the  strains  and  turning  friction  so  that 
the  swing  is  made  more  rapidly.  To  do  this,  the  hoisting  drum 
is  geared  directly  to  the  engine,  and  from  the  drum  the  rope  is 
lead  over  a  sheave,  suspended  from  the  A-frame,  to  a  differential 
drum  placed  on  the  boom.  This  differential  drum  is  made  up 
of  three  concentric  drums,  one  of  large  diameter  in  the  centre 
carrying  the  single  rope  from  the  hoist,  and  two  drums  of  a 
common  smaller  diameter,  rigidly  attached  to  both  sides  of  the 
former,  carrying  the  twin  ropes  over  the  head  sheave  to  the  dip- 
per back.  Their  respective  diameters  are  about  7  ft.  and  3J^  ft. 
Winding  the  rope  on  the  hoisting  drum  causes  the  hoisting  rope 
to  run  off  the  large  diameter  of  the  differential  drum,  and  the 
twin  ropes  atached  to  the  dipper  to  wind  on  the  smaller  drums. 
This  difference  in  drum  diameters  causes  a  slower  but  heavier 
pull  to  be  exerted.  The  rope,  running  from  the  sheave  suspended 
from  the  A-frame  to  the  large  differential  drum,  is  located  in  the 
line  of  the  turntable  axis,  so  that  no  guide  pulleys  are  required 
to  act  as  guides  for  the  rope  twist.  Thus  when  digging  strains 
are  exerted,  the  tendency  of  the  rope  between  these  sheaves  to 
exert  an  upward  pull  on  the  differential  drum  and  lower  end  of  the 
boom  relieves  weight  from  the  turntable.  This  is  said  to  amount 
to  about  15  tons  when  digging  with  a  3-cu.  yd.  dipper,  and  7 
tons  with  the  dipper  empty.  All  three  engines  are  of  the  double 
reversing  type.  With  a  40°  normal  angle  and  15-ft.  boom, 
a  clear  lift  of  18  ft.  is  had.  The  boiler  is  of  the  locomotive 
type.  The  machine  is  self-propelling  and  the  clutches  are  steam 
driven.  There  are  also  side  bearings  which  screw  up  horizon- 
tally making  a  wedge-like  contact  between  the  tread  of  the  truck- 
wheels  and  sides  of  the  car  bed.  This  gives  the  machine  a  rigid 
bearing  on  the  rails  across  the  full  width  of  the  track  gauge 
and  prevents  rocking  or  tilting. 

Wire-rope  shovels  of  this  class  have  not  come  into  the  general 
use  enjoyed  by  those  of  the  chain  type.  For  the  large  revolving 
shovels,  however,  wire  rope  is  exclusively  used  for  hoisting. 

Electric  Driven  Shovel. — Until  recent  years  steam — or  in 
a  very  few  cases  compressed  air — was  the  motive  power  employed 
on  all  of  these  excavators,  but  the  progress  made  in  electrically 
driven  shovels  has  been  so  marked  that  the  present  day  electric 
machines  leave  little  to  be  desired. 

Electric  shovels  of  all  sizes  are  now  built  by  the  leading  manu- 


THE  POWER  SHOVEL  31 

facturers  and,  where  electric  power  is  reasonably  cheap,  they 
are  rapidly  coming  into  general  use.  During  the  few  years 
they  have  been  in  service  they  have  been  highly  satisfactory 
and  dependable. 

These  shovels  are  divided  into  three  classes;  the  friction 
electric,  operated  by  a  single  constant-speed  motor  with  friction 
clutches;  the  three  or  four  motor  direct-current  equipment;  and 
the  three  or  four  motor  alternating-current  equipment.  The 
first  class  is  little  used  as  it  is  much  slower  than  steam,  though 
about  as  cheap  in  operation. 

Either  direct  or  alternating  current  may  be  used.  The 
tendency  of  present  practice  is  strongly  in  favor  of  alternating 
current  when  it  is  available,  and  to  date  there  is  a  large  pre- 
ponderance of  alternating  current  machines  in  actual  service. 
This  preference  is  due  to  the  greater  ruggedness  of  the  A.  C. 
motor  and  to  the  elimination  of  all  commutators  and  of  the  motor 
generator  required  to  supply  direct  current. 

The  electrically  operated  shovel  has  a  number  of  strong  ad- 
vantages over  the  steam-driven  shovel.  The  operation  is  quieter, 
steadier,  quicker,  cleaner  and  safer  from  sparks  and  fire  than  that 
of  the  steam  shovel.  None  of  the  troubles  due  to  bad  or  inter- 
rupted water  are  encountered;  no  pipe  lines  or  hauling  of  water 
or  fuel  are  required;  no  fireman  is  needed;  during  cold  weather 
the  steam  driven  machine  must  be  carefully  watched,  as  must 
also  the  pipe  lines,  to  avoid  freeze-ups;  on  the  steam  machine  some 
steam  must  be  kept  up,  even  while  idle,  and  the  usual  "  stand- 
by" losses  of  firing-up  and  after-use  come  in  with  the  attendant 
expense  for  fuel  and  water.  The  electric  machine  may  be 
started  working  as  soon  as  the  crew  arrives,  and  current  con- 
sumption ceases  when  the  motors  are  stopped.  It  is  of  course 
necessary  to  provide  transmission  lines  and  power  cables  to  the 
shovels,  but  the  expense  of  maintaining  them,  or  moving  them 
about,  is  comparatively  small.  In  some  cases  where  current 
has  to  be  supplied  to  electrically  driven  shovels  from  a  long 
distance,  or  at  an  unsuitably  low  voltage  or  through  an  existing 
feeder  of  inadequate  capacity,  the  operation  of  the  electric 
shovel,  which  is  intermittent  and  characterized  by  high  peaks, 
may  cause  objectionable  disturbance  of  the  electric  supply  to 
other  consumers  on  the  same  electric  feeder. 

Except  for  the  changes  required  to  install  the  electric  equip- 
ment replacing  the  steam,  the  design  of  the  machines  is  practi- 


32  STEAM  SHOVEL  MINING 

cally  the  same.  Instead  of  the  usual  steam  engines,  independent 
motors  are  provided  for  the  hoisting,  swinging  and  crowding 
functions  on  all  except  the  small  machines,  where  the  first  two 
motionsrmay  be  taken  care  of  by  a  single  motor.  The  hoisting 
and  swinging  motors  are  mounted  directly  on  the  rear  of  the 
shovel  platform  and  are  geared  to  the  drums  through  reducing 
gears.  The  thrust  motor  is  mounted  on  the  upper  side  of  the 
boom,  and  geared  to  the  pinion-gears  through  proper  reducing 
gears.  Control  of  the  motions  is  effected  by  individual  electric 
controller  levers  operated  in  the  same  manner  as  in  steam  mach- 
ines. To  protect  the  motors  and  machinery  from  careless  hand- 
ling or  severe  overload,  automatic  cut-out  relays  are  put  in  the 
line  so  that  under  such  conditions,  the  motors  will  be  stopped 
and  the  load  held.  The  motors  may  then  be  restarted 'by  means 
of  the  controllers. 

Notwithstanding  the  fact  that  the  electric  shovel  has  been 
developed  to  a  point  where  its  performance,  control,  and  dependa- 
bility is  fully  equal  to  that  of  the  corresponding  steam  machines, 
its  general  adoption  has  been  retarded  through  a  perfectly  natural 
caution,  remembering  that  the  steam  machines  have  been 
wonderfully  developed,  have  shown  enormous  cost  reductions 
over  older  methods  of  excavation  and  that  the  training  of  both 
the  machine  operators  and  those  in  charge  of  such  work  has 
almost  entirely  been  with  the  steam  machines.  Furthermore, 
at  many  places  where  electric  power  is  cheaply  available,  the 
companies  have  considerable  capital  invested  in  good  steam 
equipment  which  still  has  a  long  efficient  working  life,  and  though 
in  the  long  run  the  expense  involved  in  changes  in  equipment 
might  be  fully  justified,  such  transitions  will  be  gradual,  and 
should  be  made  with  balanced  judgment. 

In  this  connection  it  is  interesting  to  note  the  shipments  of 
electric  shovels  made  by  the  larger  manufacturers  and  some  of 
the  localities  to  which  they  were  sent.  Other  makers  have  also 
furnished  electric  shovels. 

Commencing  in  1912  and  extending  to  April,  1919,  the  Bucy- 
rus  Co.  have  shipped  twenty  electric  railroad  shovels,  five  large 
electric  revolving  shovels,  and  nine  small  electric  revolving 
shovels.  Shipment  was  made  of  three  in  1912,  two  in  1913, 
three  in  1914,  two  in  1915,  nine  in  1916,  four  in  1917,  eight  in 
1918,  and  three  in  the  early  part  of  1919. 

Of  the  railroad  shovels  seven  were  Type  103-C,  six  were  Type 


THE  POWER  SHOVEL  33 

100-C,  two  were  Type  70-C,  and  the  remaining  five  were  one 
each  of  Types  60-C,  68-C,  40-R,  95-C,  and  Cl.B.  Vulcan.  All 
the  railroad  shovels  use  alternating  current  except  the  Vulcan 
which  uses  220-volt  direct  current.  These  shovels  were  shipped, 
eight  to  the  Luossavaara  Kiirunavaara  Akt.,  Sweden,  four  to  the 
Chile  Exploration  Co.,  Chile,  three  to  the  Hydro-Electric  Power 
Commission,  Niagara  Falls,  and  the  remaining  five  singly  to 
different  purchasers. 

The  large  revolving  shovels  are  all  Type  225-B,  A-C.  machines, 
three  of  which  were  shipped  to  the  Hydro-Electric  Power  Com- 
mission, Niagara  Falls,  one  to  the  Pittsburg  and  Midway  Coal 
Co.,  Kansas,  and  one  to  the  Chile  Exploration  Co. 

Of  the  small  electric  revolving  shovels,  two  were  Type  14-B, 
three  Type  25-B,  three  Type  35-B,  and  one  Type  18-B.  All  use 
alternating  current  except  one  14-B,  which  uses  550-volt  direct 
current.  Two  were  shipped  to  the  Russian  Reclamation  Service 
in  Turkestan,  two  to  the  Locust  Mt.  Coal  Co.,  Penna.,  and  the 
others  singly  to  other  purchasers. 

The  Marion  Steam  Shovel  Co.  from  1908  to  1919  inclusive  has 
shipped  nine  railroad  electric  shovels,  ten  large  electric  revolving 
shovels  and  twenty-six  small  electric  revolving  shovels.  Of 
these  45  shovels  the  year  of  shipment  of  six  is  not  known,  though 
it  was  quite  recent,  but  the  others  were  shipped,  one  in  1908, 
three  in  1909,  one  each  in  1910,  1913,  and  1914,  five  in  1915, 
ten  in  1916,  three  in  1917,  ten  in  1918  and  four  in  1919. 

Of  the  railroad  shovels  three  were  Model  40  using  A-C,  and 
were  shipped  to  the  Los  Angeles  Board  of  Public  Works.  The 
others  all  use  550-volt  direct  current,  two  being  Model  51,  two 
Model  91,  and  one  each  Models  41  and  92,  and  were  shipped 
one  to  Norway,  one  to  Chile,  two  to  Sanborn,  N.  Y.,  and  one 
each  to  Cambria,  N.  Y.  and  Niagara  Falls. 

The  large  revolving  shovels  all  use  230-volt  direct  current, 
one  was  Model  271  and  nine  were  Model  300,  and  all  were  shipped 
to  coal  stripping  operations  in  Ohio  and  Pennsylvania. 

Of  the  small  revolving  shovels,  six  were  Model  28  and  one  of 
these,  shipped  to  the  Government  of  the  Philippine  Islands, 
uses  230-volt  direct  current,  the  others  all  using  alternating 
current.  One  Model  28  was  shipped  to  the  United  Verde  Copper 
Co.  in  Arizona  for  use  underground.  Six  small  revolving  shovels 
were  Model  31,  all  using  A-C  except  one  230-volt  D-C  machine, 
shipped  to  the  Canadian  Klondyke  Mining  Co.,  and  fourteen 


34 


STEAM  SHOVEL  MINING 


were  Model  36  all  using  alternating   current  and  almost  all 
shipped  to  coal  mining  operations  in  Ohio  and  Pennsylvania. 

In  most  of  the  electric  installations  now  being  made,  fuel  is 
so  expensive  as  to  leave  no  doubt  as  to  the  economy  of  electric 
equipment,  whereas  electric  power  is  of  quite  moderate  cost, 
frequently  being  as  low  as  %  c.  per  KWH.  Based  on  results 
from  shovels  long  in  operation,  it  has  been  found  that  the  average 
current  consumption  per  ton  of  material  excavated  varies  from 
0.3  KWH  to  0.5  KHW.  In  difficult  digging  or  poorly  shot 
banks,  this  power  consumption  will  be  exceeded,  since  most  of 
the  shovel  movements  do  not  deliver  any  tonnage.  The  above 
figures  cover  a  reasonable  average  in  hard  rock. 

A  COMPARISON  OF  ELECTRIC  SHOVELS   OPERATING  IN  THE   HARD  IRON 

ORES  OF  SWEDEN  is  QUOTED  FROM  THE  BUCYRUS  COMPANY 

(THE  POWER  CONSUMPTION  is  SOMEWHAT  HIGH) 


German  make 

Bucyrus  make 

Maximum  peak  
Next  4  peaks.  .  .  . 

390  KW 
370  KW 
36.5  tons 
105.4   KW 
20  min. 
35.1 
0.96 

380  KW 
340  KW 
36.5  tons 
105.4   KW 
22  min. 
38.6 
1.06 

520  KW 
460  KW 
37.4  tons 
157  KW 
9}£  min. 
24.8 
0.662 

480  KW 
420  KW 
36.0  tons 
164  KW 
11%  min. 
30.8 
0.855 

Amount  of  excavation 

Average  load  

Time  to  load  5  cars  
KWH  

KWH  per  ton 

The  following  comparison  shows  the  estimated  difference  in 
the  cost  of  operation  per  day  of  10  hr.  of  a  100C  Bucyrus  shovel, 
whether  operated  by  A-C.  electric  motors  or  with  boiler  equipped 
with  oil  burner  or  for  coal. 

ELECTRIC 

Runner $5 . 00 

Craneman 3 . 60 

Fireman • . 

5  Pitmen  7 . 50 

Oil  (18  bbl.  @  $1.50-42  gal./bbl.)        

Electricity  (1400  KWH  @  l£> . . .        14 . 00 

Coal  (4  tons  @  $5.00) 

Oil  and  waste 1 . 00 

Repairs  and  renewals 1 . 50 

Water.. 


OIL  BURNING 

COAL 

$5.00 

$  5.00 

3.60 

3.60 

2.40 

2.40 

7.50 

7.50 

27.00 

1.50 
2.50 
2.00 


20.00 
1.50 
2.50 
2.00 


Total $32.60 


$51.50 


$44.50 


THE  POWER  SHOVEL 


35 


It  is  assumed  that  168  gal.  of  oil  is  equivalent  to  1  ton  of  coal. 
Under  favorable  conditions  the  power  consumption  could  be 
reduced  all  around  to  three  fourths  of  the  above.  If  electric 
power  costs  2c.  per  KWH  the  operating  cost  of  the  electric 
shovel  would  be  increased  to  $46.60  per  shift  and  would,  there- 
fore, be  higher  than  the  steam  shovel  fired  by  coal,  but  less  than 
if  fired  by  oil.  Fuller  costs  will  be  given  in  another  chapter. 

Fig.  101  interestingly  shows  the  comparative  operating  power- 
costs  with  variable  cost  for  coal  and  electric  power. 

It  may  be  here  mentioned  that  the  price  of  an  electric  shovel, 
of  the  100C  class  was  about  $20,500  at  the  works  in  1915.  This 
covered  motors  and  controllers  sutable  for  alternating  3-phase, 


Cost  of  Coal  in  Dollars  per  Ton 

M  0>          Jk  <J1  O          -4  0> 


FIG.   10. — Comparative  power  cost  curve. 

60-cycle,  440-volt  current  but  no  transformers.  This  price  was 
about  one-third  higher  than  for  the  same  class  of  steam  machine. 
Electro-Hydraulic — Driven  Shovels. — Desiring  to  simplify 
the  control  and  reduce  to  a  minimum  the  heavy  surges  of  cur- 
rent taken  by  the  motors,  the  electro-hydraulic  shovel  has  been 
designed.  This  first  consisted  in  replacing  the  steam  machinery 
of  a  standard  shovel  with  a  motor-driven  centrifugal  pump,  a 
pressure  tank,  an  air  tank,  a  small  air  compressor  and  water 
cylinders  with  plungers,  pistons  and  valves.  Later  it  was  found 
that  the  tanks  and  air  compressor  were  not  required,  as  sufficient 
capacity  could  be  obtained  without  the  use  of  compressed  air; 

1  ROGERS,  H.  W.:  The  Application  of  Electric  Motors  to  Shovels,  T.A.I.- 
M.E.,  pp.  299-309,  Feb.,  1914. 


36  STEAM  SHOVEL  MINING 

the  capacity  of  a  centrifugal  pump  increasing  rapidly  with  a 
decrease  in  head. 

The  shovel  so  equipped  by  the  Penn  Iron  Mining  Co.,  of 
Vulcan,  Mich.1  operates  as  follows:  The  dipper  is  hoisted  by 
means  of  one  large  single-acting  cylinder  and  plunger.  Double 
hoisting  ropes  pass  around  two  sheaves  at  the  outer  end  of  the 
plunger  and  these  ropes  have  one  end  fastened  to  the  dipper 
while  the  other  is  anchored  to  the  front  flange  of  the  hoisting 
cylinder.  With  this  arrangement  the  dipper  travel  is  just 
twice  that  of  the  plunger.  The  weight  of  the  dipper  pulls  the 
plunger  back  on  the  exhaust  stroke.  Swinging  the  boom  is 
effected  by  means  of  a  double-acting  cylinder  with  a  piston  rod 
extending  through  each  cylinder  head  and  with  a  sheave  at 
each  end  of  the  rod.  Passing  around  the  front  of  the  swing 
circle  is  a  rope,  each  end  of  which  is  led  around  one  of  the  sheaves 
on  the  ends  of  the  rod  and  then  anchored  to  the  car  body.  The 
thrusting  is  done  by  the  four  piston  rods  of  four  thrusting  cylin- 
ders directly  connected  to  the  dipper  handle  in  such  a  way  as 
to  give  perfect  balance  around  the  shipper  shaft.  Swivels  and 
sleeve-joint  piping  permit  the  boom  to  operate  freely.  To 
trip  the  dipper,  an  ingenious  solenoid  tripping  device  is  placed 
near  the  front-end  of  the  dipper  handle  and  works  the  tripping 
latch.  This  shovel  is  operated  entirely  by  one  man;  with  one 
lever  he  controls  the  thrust,  with  another  he  hoists,  while  by 
lowering  his  right  hand  on  the  first  lever  he  touches  a  button 
which  causes  the  solenoid  to  trip  the  dipper.  Foot  levers 
control  the  swing  of  the  boom  to  the  right  or  left,  and,  when 
equally  compressed,  the  valves  automatically  centre  the  boom. 
The  controller  handle  rf or  operating  the  motor  which  drives  the 
centrifugal  pump  supplying  power  to  the  shovel  is  conveniently 
located  near  the  right  hand  lever. 

Loading  from  a  stock  pile,  3000  tons  per  10-hr,  shift  has  often 
been  handled  with  only  fair  train  service.  The  wattmeter 
record  shows  the  dipper  speed  to  be  from  3  to  4  per  minute  and 
the  power  consumption  to  be  from  about  80  to  130  KW. 

The  advantages  of  this  shovel  are:  its  few,  simple  and  slow 
moving  parts;  absence  of  gears,  clutches,  brakes  and  drums; 
comparative  cleanliness  and  silence  of  operation;  need  of  but 
one  man  to  operate;  greatly  reduced  peak  load  when  operating; 

1  F.  H.  ARMSTRONG:  T.A.I. M.E.,  Feb.,  1916.  Iron  Trade  Review,  Feb.  27, 
1916,  p.  393. 


THE  POWER  SHOVEL  37 

no  power  cost  when  idle;  smooth  and  accurate  control.  As 
the  leakage  of  the  liquid  is  small,  an  hydraulic  oil  that  will  not 
freeze  can  be  safely  used  in  cold  weather.  While  yet  somewhat 
in  the  experimental  stage,  for  the  use  to  which  this  shovel  has 
been  put,  it  seems  to  have  much  to  recommend  it. 

Oil-Engine-Driven  Shovels. — Oil  engines  of  the  various 
types  are  supplied  if  desired  by  several  of  the  shovel  manufac- 
turers, especially  for  the  lighter  machines.  So  far,  this  class  of 
motive  power  has  not  come  into  very  wide  use  and  the  condi- 
tions where  it  shows  to  advantage  are  exceptional. 

COMPETING  MACHINES 

General — Field. — Power-shovels  have  been  competing  with 
aerial  tramways,  machine-scrapers,  clam-shell,  orange-peel  and 
bucket  excavators,  dry-land  dredgers  and  many  other  similar 
devices  in  the  general  excavating  fields,  but  the  results  obtained 
with  shovels  have  usually  been  much  more  satisfactory  in  mining. 

Dredges. — Such  machines  as  the  great  floating  dipper  and 
bucket  dredges,  the  hydraulic  and  deep-water  dredges,  occupy 
as  a  rule  a  field  distinct  from  that  of  the  shovel. 

The  dipper  dredge,  designed  to  carry  dippers  of  from  2  to  15 
eu.  yd.  capacity,  is  used  under  some  conditions  for  drainage 
and  irrigation  ditch  excavation,  and  for  large  canal,  inland  lake 
and  harbor  dredging.  It  is  especially  useful  and  economical 
on  subaqueous  rock  work  as  great  power  can  be  concentrated  at 
one  spot.  In  the  Panama  Canal  there  were  a  number  of  15-cu. 
yd.  dipper  dredges  at  work  on  the  slides. 

The  hydraulic  or  suction  dredge  is  the  most  economical  device 
for  removing  great  quantities  of  sand,  loam,  clay  or  gravel  from 
river  beds,  lake  bottoms  or  harbors.  It  has  a  much  greater 
capacity  than  any  other  type  of  dredge,  and  is  able  to  dispose  of 
the  material  by  means  of  pipe  lines,  at  great  distances  from  the 
point  of  excavation.  The  usual  sizes  have  suction  pipes  of 
from  12  to  36  in.  diameter,  and  are  used  on  the  Great  Lakes, 
New  York  State  Barge  Canal  and  many  other  places. 

Placer-dredges,  built  with  buckets  of  from  2J£  cu.  ft.  to  16  cu. 
ft.  capacity,  are  employed  in  many  parts  of  the  world  for  digging 
gravels,  hard-pan  and  decomposed  rock  forming  the  bottoms  of 
present  and  former  water  courses.  They  have  great  capacity- 
some  over  300,000  cu.  yd.  per  month — and  do  their  work  cheaply 


38  STEAM  SHOVEL  MINING 

—at  times  as  low  as  2^  c.  per  cu.  yd.  Their  greatest  mining  use 
is  in  dredging  for  gold,  and  they  may  be  found  on  this  work  in 
California,  Alaska,  South  America  and  other  countries. 

In  removing  overburden  from  some  of  the  brown-coal  deposits 
in  Germany  a  continuous-bucket  excavator,  similar  in  principal 
to  the  Parsons  trench  excavator  is  used.  The  ladder  and  bucket 
arrangement  is  designed  so  that  the  empty  buckets  descend  on 
the  upper  side  of  the  ladder,  mouth  down,  while  the  loaded 
buckets  are  drawn  up  on  the  lower  side.  The  buckets 
discharge  the  spoil,  upon  passing  around  the  upper  sprocket 
wheel,  into  a  hopper,  which  in  turn  discharges  into  the  spoil 
cars  running  beneath.  This  machine  is  *  self-propelling  and 
supported  by  trucks  which  run  on  a  double  track  along  the  pit 
edge.  Between  the  excavator  tracks  runs  a  third  track  on  which 
the  spoil  cars  are  run.  These  machines  are  built  in  several  sizes" 
weighing  from  12  to  70  tons  and  suitable  for  making  cuts  ranging 
in  depth  from  15  to  45  ft.  with  buckets  of  from  l^  to  8^  cu.  ft. 
capacity  and  digging  capacity  in  medium  soil  of  from  17  to  200 
cu.  yds.  per  hour.  The  continuous-bucket  excavator  is  satis- 
factory where  the  overburden  is  soft  and  free  from  boulders 
and  rock.  In  this  respect  it  is  similar  to  the  drag-line  excavator 
and  has  some  additional  features  of  advantage  in  its  operation, 
but  it  has  limitations  in  radius  of  action  and  disposition  of* 
overburden.  In  Germany  the  cost  of  removing  overburden  with 
these  machines  was  estimated  to  be  from  6  to  10  c.  per  cu.  yd. 

Dragline  Excavators. — Probably  the  nearest  direct  competitor 
of  the  power-shovel  in  America  is  the  dragline  excavator.  One 
of  Marion  design  is  illustrated  by  Fig.  11.  It  has  been  exten- 
sively used  in  irrigation  and  drainage  ditches,  levee  and  dam 
building,  making  railroad  fills  and  in  stripping  quicksands  and 
gravel  overburden  from  bodies  of  ore  and  coal.  It  has  a  re- 
markably wide  radius  of  action  and  can  deposit  material  a  long 
distance  from  the  cut.  Thus  it  may  travel  parallel  to  its  work, 
digging  from  one  side  and  depositing  on  the  opposite,  without 
throwing  much  weight  on  a  weak  bank.  It  has  the  advantage 
of  digging  far  below  the  level  on  which  it  stands,  so  that  in  case 
of  floods  or  high  ground-water  level,  the  excavation  may  be 
continued,  whereas  a  steam  shovel  would  be  " drowned  out." 
Its  wide  reach  eliminates  frequent  moving  and  may  even  elimi- 
nate hauling  of  the  excavated  material.  These  machines  work 
around  a  complete  circle,  as  do  the  revolving  steam  shovels. 


THE  POWER  SHOVEL 


39 


40  STEAM  SHOVEL  MINING 

They  are  economical  of  labor  as  only  one  runner  and  one  fire- 
man are  required.  The  character  of  material  which  it  handles, 
however,  must  be  much  looser  or  softer  than  that  which  can  be 
excavated  with  a  steam  shovel  without  blasting,  and  it  is  doubt- 
ful if  its  daily  capacity  will  come  up  to  that  of  the  shovel.  These 
two  factors  may  have  a  very  important  bearing  on  the  total 
cost  of  the  problem. 

The  machinery  is  designed  along  the  same  line  as  on  shovels. 
The  bucket  however,  is  of  different  design  from  the  shovel 
dipper  and  is  hoisted  by  a  three-part  line,  one  part  of  which 
leads  to  the  bail.  By  braking  this  line  dumping  is  effected,  as 
the  continued  hoisting  of  the  other  two  lines  raises  the  back 
of  the  bucket  and  causes  it  to  tip  upside  down.  The  fairlead 
consists  of  two  horizontal  sheaves,  mounted  on  a  casting  at  the 
front  sill  of  the  machine,  and  two  vertical  sheaves  carried  in  a 
swinging  frame  pivoted  to  this  casting.  This  frame  takes  the 
direction  of  the  dragline  and  maintains  a  straight-lead  at  all 
times. 

By  making  a  few  changes,  a  clam-shell  or  orange-peel  bucket 
may  be  used  if  desired  instead  of  the  usual  bucket. 

Standard  sizes  in  this  machine,  as  built  by  the  Bucyrus 
Company,  are  given  in  Table  8. 

The  longer  the  boom  the  smaller  is  the  capacity  of  the  bucket 
for  any  given  class.  Some  especially  large  machines  have  been 
built  with  booms  up  to  150  feet  long  and  some  handle  buckets 
holding  as  much  as  8  cu.  yds.  Their  shipping  weight  ranges 
from  75  to  135  tons.  Some  are  mounted  on  skids  and  rollers, 
which  is  considered  standard;  others  on  caterpillar  traction, 
which  eliminates  the  carrying  of  plank  and  rollers  and  facilitates 
moving  over  difficult  ground;  still  others  are  mounted  on  trucks, 
of  the  four-wheel  equalizing  type.  The  second  method  is  self- 
propelling,  while  with  the  other  two,  the  machine  usually  pulls 
itself  ahead  by  means  of  anchoring  the  bucket  and  then  pulling 
on  the  dragline.  The  standard  power  is  steam,  but  electric 
motors  or  even  oil  engines  may  be  substituted  if  desired.  Table 
8  gives  the  abstract  specifications,  and  Table  9  the  working 
dimensions  of  standard  Bucyrus  dragline  excavators. 


THE  POWER  SHOVEL 


41 


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MECHANICAL  EQUIPMENT  43 

The  dragline  excavator,  under  favorable  conditions,  will  give  a 
good  account  of  itself,  but  it  generally  occupies  a  different  field 
from  that  held  by  the  power  shovel. 

In  concluding  this  chapter  of  description,  it  may  be  said 
that  while  other  types  of  excavators  are  more  suitable  for  certain 
special  conditions,  the  power  shovel  is  to  date  by  far  the  most 
suitable  and  efficient  excavator  for  the  greatest  range  of  big 
excavation  work. 


CHAPTER  II 

MECHANICAL  EQUIPMENT 

GENERAL   CONSIDERATIONS   GOVERNING  THE   SELECTION 
OF  EQUIPMENT 

Considering  in  a  broad  way  the  selection  of  equipment  for 
open-pit  mining,  the  factors  of  first  importance  are;  the  magni- 
tude, output  and  probable  life  of  the  undertaking;  the  supply 
and  character  of  the  labor;  the  form  of  power  to  be  employed 
and  the  conditions  under  which  it  will  be  obtained  and  operate; 
the  amount  of  capital  available  or  justifiable  to  expend;  the 
possibilities  of  increase  or  fluctuations  in  the  scale  of  operations; 
the  actual  working  conditions  expected  to  be  met  with  in  the 
pit — such  as  height  and  width  of  benches,  grades  and  curvature 
of  trackage,  disposal  of  overburden  and  ore,  class  of  material, 
climatic  and  topographic  conditions,  water  supply  and  drainage; 
cost  and  conditions  under  which  various  supplies  are  obtainable 
and  under  which  product  is  sold;  any  conditions  relating  to 
time  allowance  for  work,  delivery  of  product,  or  government 
laws  to  be  complied  with. 

The  actual  operation  of  a  shovel  mine  is  largely  a  combination 
of  mechanical  and  civil  engineering.  Much  assistance  in  the 
selection  of  equipment  can  often  be  had  by  consulting  with  the 
engineers  of  the  best  operated  open-pit  mines  and  with  the  fore- 
most manufacturers  of  shovel  and  other  required  equipment. 

On  a  given  job,  it  is  as  a  rule  better  to  adopt  and  then  adhere 
to  a  make,  type  and  size  of  machine,  which  may  be  called  stan- 
dard, than  to  install  a  number  of  different  makes,  types  or  sizes. 
Though  experimentally  interesting,  different  shovel  designs  add 
greatly  to  the  stock  of  spare  parts  which  must  be  kept  on  hand 
and  cause  some  confusion  in  shop  repair  work  and  in  inter- 
changing the  operating  crews.  The  rule  of  standardization 
of  equipment  is  applicable  to  almost  all  of  the  major  equipment. 
If  experimental  work  on  equipment  be  undertaken,  it  should 
be  done  in  a  limited  way  and  carefully  watched,  in  which  case 
the  results  may  lead  to  progressive  improvement  and  be  of 

44 


MECHANICAL  EQUIPMENT  45 

actual  value.     Operations  carried  on  by  others  should  be  watched 
and  analyzed. 

It  is  sometimes  possible  to  buy  second-hand  equipment, 
discarded  from  government  or  railroad  work.  If,  on  careful 
inspection,  such  equipment  be  found  in  good  condition  and  well 
adapted  to  the  requirements,  some  economy  can  be  made  on 
the  first  cost ;  but  if  the  work  be  large  and  will  cover  a  long  time 
it  is  generally  more  economical  in  the  long  run  to  purchase 
new  and  efficient  machinery  fully  adapted  to  the  work. 

It  is  an  impressive  fact  that  the  general  trend  of  practically 
all  of  the  equipment  is  ever  towards  heavier  and  larger  machines. 
First  cost  of  equipment  is  less  important  thari  the  unit  cost  of 
excavation. 

The  various  equipment  units  will  be  considered  individually 
and  collectively. 

SHOVELS 

Principle  Governing  Factors. — The  best  shovel  to  select 
for  a  given  piece  of  work  will  depend  on  the  amount  and  character 
of  material  to  be  excavated,  its  disposal,  the  height  and  width 
of  the  cuts  or  benches,  the  class  of  operating  labor  available 
and  the  class  of  power  that  is  most  economical. 

Pit  Working  Conditions. — If  the  excavation  is  to  be  a  large 
one  with  deep  cuts,  heavy  expensive  shovels  are  justified  because 
of  their  greater  output  and  cheaper  unit  costs.  A  shovel  ex- 
cavating 1200  cu.  yd.  per  shift  will  show  a  unit  operating  cost 
about  two-thirds  that  of  a  shovel  excavating  only  800  cu. 
yds.  per  shift,  assuming  that  efficient  train  service  be  afforded 
for  the  prompt  loading  and  supplying  of  cars.  If  the  material 
be  hard  and  inclined  to  break  coarse  or  if  the  shovel  be  expected 
to  dig  moderately  compact  material  without  the  aid  of  blasting, 
a  heavy  rugged  shovel  with  medium-sized  dipper  should  give 
the  best  results.  If  the  material  be  soft  or  easy  to  dig  a  larger 
dipper  may  be  employed,  and  if  the  train  service  be  good  a  fast 
loading  shovel,  such  as  the  Atlantic,  may  give  the  greatest 
output.  If  the  cuts  are  to  be  very  light  a  small  shovel  may  be 
more  economical  as  it  is  more  easily  moved. 

If  working  conditions  permit,  the  weight  of  shovel,  length  of 
boom  and  length  of  dipper-stick  should  bear  an  approximate 
relationship  to  the  height  and  width  of  the  banks  and  benches 
it  is  proposed  to  carry.  A  working  example  of  this  relationship 
for  straight  bank-loading  is  shown  on  Fig.  12. l  In  box  or 

1  Nevada  Consolidated  Copper  Co.,  Dec.  15,  1915. 


46 


STEAM  SHOVEL  MINING 


" thorough-cutting,"  or  excavating  below  the  loading-track,  the 
relationship  is  worked  out  as  shown  in  Fig.  13.  As  a  rule,  the 
best  height  of  bank  is  about  equal  to  the  width  of  cut  which  the 
shovel  can  take,  thus,  with  a  34-ft.  boom,  the  cut  will  be  about 
45  ft.  and  the  height  of  bank  about  45  ft.;  with  a  40-ft.  boom 
these  dimensions  can  be  increased  to  say  60  ft.  More  will  be  said 


[Shovel 

Weight, 
tons 

Class 

Length 
boom, 
ft. 

Length 
dipper- 
stick, 
ft. 

a 

6 

c 

d 

e 

/ 

G-l 

95 

C 

32 

22  K 

61' 

68' 

18' 

27' 

80' 

11' 

1 

100 

B 

34 

24 

45' 

45' 

22' 

29' 

43' 

.  11' 

2 

70 

B 

28 

18 

50' 

50' 

19M' 

24' 

75' 

11' 

3 

100 

B 

32 

24 

68' 

73' 

17' 

31' 

87' 

11' 

4 

100 

B 

32 

24 

49' 

41' 

19' 

30' 

75' 

11' 

5 

100 

C 

32 

24 

54' 

54' 

18' 

32' 

6'  . 

11' 

6 

100 

C 

32 

22  M 

48' 

40' 

20' 

30' 

6' 

11' 

7 

100 

C 

32 

24 

46' 

40' 

18' 

34' 

8' 

11' 

8 

100 

C 

34 

24 

60' 

61' 

21' 

31' 

11' 

11' 

FIG.  12. — Working  example  of  shovel  benches  bank  loading. 

later  as  to  the  best  height  of  banks,  but  if  this  point  is  decided 
then  it  must  be  kept  in  mind  when  drawing  up  shovel  specifi- 
cations. Practical  working  conditions  very  often  cause  this  re- 
lationship to  be  totally  disregarded  but  the  results  will  then  be 
less  satisfactory. 

Class  of  Operating  Labor. — If  the  operating  labor  be  in- 
experienced and  careless  and  the  digging  difficult,  the  idea 
employed  in  the  construction  of  some  shovels,  by  which  the 


MECHANICAL  EQUIPMENT 


47 


engines  are  so  designed  that  they  will  stall  before  breaking 
something,  is  a  very  good  one.  In  the  hands  of  such  a  runner 
the  repairs  may  be  much  less  on  a  shovel  so  designed.  In  the 
hands  of  a  first-class  runner  the  more  powerful  engines  employed 
on  other  designs  should  give  equally  good  results  and  perhaps 
show  a  greater  capacity.  The  idea  employed  in  still  other  shovels 
of  exerting  a  horizontal  and  pivotal  motion  to  the  dipper  gives 
very  satisfactory  results  though  these  shovels  are  of  compara- 
tively smaller  capacity. 


f- 


SOFT- 


27J*_ 


%w 


25. 


23* 


10* 


n't 


7f! 


33n4SF14IFT.2<AH 


'£40'* 


28*  36% 


2M36 


m. 


25 


»* 


7?¥ 


35 


34 


33*4 


23*3& 


26 


401*  20 
3&fy  19 


36*  J8 


A 


33^ 


m. 


29&29£ 


29 


27 


Vs 


JT 


2M 


f2Ve_ 


FIG.  13. — Reach  of  shovels  in  thorough-cutting. 

Power.  Steam. — The  power  to  be  adopted  for  pit  equip- 
ment may  be  steam,  electricity,  compressed  air,  or  oil  engines. 
The  first  method  is  the  oldest,  simplest,  best  understood  by  the 
average  operator  and  probably  the  most  dependable.  The 
firing  may  be  done  with  wood,  coal  or  fuel  oil,  depending  on  the 
relative  economy  as  applied  to  each  particular  installation. 
There  are  disadvantages  sometimes  found  in  the  high  cost  of 
fuel,  additional  operating  force  required,  difficulty  in  securing 
good  boiler  feed-water  and  in  keeping  the  water  supply-lines 
open  in  severe  winter  weather.  Steam  is  still  to  be  found  in 
the  great  majority  of  installations,  and  unless  other  power  can 
be  shown  to  have  decided  advantages  over  steam,  it  is  to  be 
recommended. 

Electric. — Electric  power  has  been  coming  more  and  more 
into  favor  because  of  its  economy  and  convenience.  Perfecting 


48          STEAM  SHOVEL  MINING 

the  motors  and  the  control  and  the  cheaper  cost  of  power  have 
been  responsible  for  this.  Comparative  operating  costs  of  steam 
versus  electric  shovels  were  given  in  Chap.  I.,  and  were  shown 
to  depend  largely  on  the  relative  costs  of  coal  and  electricity, 
though  considerable  operating  labor  is  also  dispensed  with  on 
the  electric  shovels.  As  the  electric-  shovel  has  many  of  its 
moving  parts  rotary  instead  of  reciprocating,  the  wear  and  tear 
on  these  is  less,  also  boiler  troubles  are  eliminated.1 

A  study  of  the  relative  cost  of  shovels  operated  respectively 
by  steam  and  by  direct  and  alternating  current  was  given  by 
Rogers2. 

This  study  was  based  on  assumptions  as  to  shovel  output,  capi- 
tal cost,  interest,  amortization,  labor,  etc.,  and  his  conclusion 
is  that  the  direct  current  shovel  will  be  always  cheaper  than 
steam,  but  that  saving  for  an  A-C  shovel  over  steam  operation 
may  come  only  from  power  saving,  which  of  course  will  depend 
in  turn  on  the  relative  cost  of  fuel  and  electric  power. 

The  103-C  shovels  used  at  Chuquicamata  are  operated  by 
alternating  current  and  require  from  .3  KWH  to  .7  KWH  per 
ton  according  to  the  character  of  the  digging,  which  is  always, 
however,  in  rock.  About  25  per  cent,  of  this  power  is  used  in 
clearing  the  pit  while  waiting  for  cars. 

They  are  fed  at  5,000  volts,  3-phase,  step-down  transformers 
being  located  on  each  shovel. 

The  equipment  on  the  latest  shovels  consists  of  one  250  h.p. 
500  volt  hoist  motor  and  100  h.p.  thrust  and  swing  motors  with 
three  100  K.W.  transformers.  The  control  is  partly  automatic, 
consisting  of  contactors  controlled  by  overload  and  jamming 
relays.  The  shovels  are  equipped  with  4-cu.  yd.  buckets  and 
can  make  20-second  cycles  under  favorable  conditions. 

Actual  costs  for  these  electric  shovels  show  that  labor  and 
repairs  cover  about  80  per  cent,  of  the  operating  cost,  cost  of 
power  being  only  10  per  cent.,  with  current  at  2%  c.  a  KWH. 
Steam  operating  costs  under  similar  conditions  show  a  total 
more  than  double,  though  with  very  high  coal  and  oil  costs. 

1  Delays  on  account  of  shovel  repairs  on  a  Bucyrus  40-R  electric  shovel 
amounted  to  3%  per  cent,  of  the  total  time,  and  only  a  small  part  of  this 
was  spent  in  attendance  on  the  motors  and  electrical  equipment.     Location, 
Granby  Mine,  Phoenix,  B.C. 

2  ROGERS,  H.  W. :  The  Application  of  Electric  Motors  to  Shovels,  T.  A.- 
I.M.E.,  Feb.,  1914,  pp.  300-309. 


MECHANICAL  EQUIPMENT  '  49 

The  steam  shovel  repairs  were  150  per  cent,  of  the  electric  shovel 
repairs  and  the  labor  somewhat  higher  than  with  the  electric 
shovel. 

The  A.C.  electric  shovels  cost  approximately  50  per  cent,  more 
than  the  steam.  As  to  whether  the  direct-current  or  alternating- 
current  equipment  is  preferable,  it  was  previously  stated  that 
considerable  difference  of  opinion  exists.  Those  advocating 
the  latter  contend  that  it  is  superior  on  account  of  greater  me- 
chanical simplicity  and  because  the  characteristics  of  the  wound- 
rotor  induction-motors  are  better  adapted  to  shovel  service 
than  are  the  characteristics  of  the  series  motors.  Both  the 
direct-current  series  motor  and  the  wound-rotor  induction 
motor,  when  provided  with  proper  resistance  in  the  circuits, 
will  nearly  approach  the  performance  of  the  steam  engine;  both 
have  good  starting  torque,  quick  acceleration  under  light  loads, 
and  reduced  speed  under  heavy  loads.  The  direct-current 
control  is  somewhat  simpler  but  the  alternating-current  control, 
with  the  resistance  automatically  cut  in  and  out  by  solenoid 
switch  control,  is  now  very  satisfactory.  The  rotors  will  either 
start  or  stall  at  maximum  torque,  and  automatic  jamming  relays 
prevent  the  current  from  reaching  the  " break-down"  point. 

It  is  desirable  to  keep  the  rotor  inertia  small,  and  for  that 
reason  two  motors  may,  if  necessary,  be  placed  on  the  hoist 
instead  of  one  larger  one,  but  it  is  questionable  whether  except 
in  the  case  of  the  largest  machines  the  saving  in  power  and  time 
are  not  more  than  offset  by  the  necessary  addition  of  a  motor  and 
other  parts. 

With  the  direct-current  motors  a  motor-generator  set  will 
usually  be  required,  but  with  the  alternating-current  motors 
three  stationery  transformers  is  common  practice.  The  latter 
arrangement  makes  for  simplicity  by  substituting  slip-rings  for 
commutators,  and  stationary  transformers  for  the  rotaries. 
Under  the  severe  conditions  of  jar  and  grit  and  dust  found  in 
all  shovel  service,  this  point  is  noteworthy.  It  is  true  that  a 
larger  excess  in  motor  capacity  must  be  provided  for  when  using 
alternating-current.  This  may  range  from  twenty  five  to  forty 
five  per  cent. 

It  is  not  the  intention  to  discuss  here  in  great  detail  such 
subjects  as  are  better  left  for  expert  argument,  but  from  the 
foregoing  and  from  the  fact  that  a  large  majority  of  the  most 
modern  large  electric,  excavators  have  been  equipped  with 


50         .STEAM  SHOVEL  MINING 

alternating-current  motors,  and  that  these  are  giving  excellent 
satisfaction,  it  is  judged  that  they  are  found  in  practice  to  be 
preferable. 

Compressed  Air. — Compressed  air  can  be  used  for  operating 
shovels  in  the  same  way  that  steam  is  employed  and  with  the 
same  engines  and  their  mechanical  advantages.  Air  is  in  many 
ways  much  superior  to  steam.  It  is  cleaner  and  does  away 
with  boiler  and  water  troubles,  at  least  at  the  shovel;  it  re- 
quires no  fireman,  no  coal  passer,  no  watchman  and  no  fuel- 
teaming.  When  electric  power  is  used  to  operate  shovels,  a 
competent  electrician  must  always  be  kept  available,  and  this 
will  be  somewhat  of  an  added  expense  in  small  installations. 
Compressed  air  can  be  transmitted  long  distances  without  any 
appreciable  pressure  loss,  provided  the  lines  are  of  ample  size 
and  kept  tight.  With  electricity  there  are  considerable  losses  in 
line  transmission  and  in  transformers  or  motor-generator  sets, 
while  the  losses  by  condensation  in  long  steam  lines  are  usually 
heavy.  A  compressor  plant  can  be  located  at  a  convenient 
point  for  handling  coal  and  water  for  the  boilers,  if  it  be  steam- 
driven,  or  at  some  central  point  if  operated  electrically.  The 
air  will  then  be  distributed  through  mains  to  the  shovels  and 
may  also  be  used  for  driving  rock-drills  for  blasting,  and  almost  any 
other  auxiliary  machinery.  Why  it  is  not  used  more  in  excava- 
tions of  great  magnitude  is  probably  due  to  prejudice,  the  ex- 
pense of  installation  of  the  plant  and  mains,  and  the  expense  of 
maintaining  the  pipe-lines.  There  is  considerable  expense  in 
winter  in  maintaining  water  lines  to  steam-shovels  and  it  is 
doubtful  if  the  air  lines  would  be  any  more  expensive.  The 
maintenance  of  electric  lines  is  much  simpler  and  comparatively 
light.  It  is  probable  that  there  is  a  field  which  may  be  more 
fully  developed,  for  air  driven  shovels,  but  at  present  there  is 
little  information  about  them  because  of  their  very  limited  use. 

Oil  Engines. — Oil  engines  are  used  on  some  of  the  smaller 
shovels.  These  engines  are  efficient,  but  unless  other  sources 
of  power  are  unattractive  the  internal  combustion  engine  is  not 
often  chosen.  They  too,  however,  offer  a  field  for  future 
development. 

The  following  is  an  example1  of  the  comparative  operating 
costs  of  steam  and  gasoline-driven,  18-ton  revolving  shovels. 

1  Thew  Automatic  Shovel  Company — Shovel  Capacity  rating  40  to  50 
cu.  yd.  per  hour. 


MECHANICAL  EQUIPMENT  51 


Operator 

PER 

STEAM 

$5  00 

SHIFT 
GASOLINE 

$5   00 

Fireman 

2  50 

Two  laborers  in  pit 

3  50 

3   50 

jruel  —  1000  to  1200  Ib    coal 

2  00 

20  gallons  gasoline 

2  50 

Oil  supplies  and  repairs 

1  00 

1  00 

Total  (exclusive  of  hauling  coal  or  water).  .      $14.00          $12.00 

Mechanically  the  operation  is  quite  satisfactory.  The  boiler 
and  steam  engine,  or  a  twenty  horse-power  electric  motor,  is 
replaced  by  a  thirty-five  horse-power  gasoline  engine. 

The  advantages  claimed,  over  steam,  for  shovels  driven  by 
oil-engines  are;  that  the  water  consumption  is  negligible  and  in 
cold  weather  a  freezing  mixture  can  be  used ;  in  some  places  the 
cost  of  fuel  is  reduced  as  gasoline  or  distillate,  being  a  more 
concentrated  fuel,  can  be  more  cheaply  transported;  there  is  an 
economy  in  labor,  as  no  fireman  or  coal  and  water  teaming  is 
required;  the  power  is  quickly  available  and  quickly  shut  off; 
there  are  no  boiler  troubles  nor  inspections;  and  a  licensed 
engineer  is  not  required. 

The  electro-hydraulic  shovel  was  described  in  Chap.  I. 
It  is  still  in  the  experimental  stage  but  has  some  very  attractive 
possibilities.  • 

Competing  Machines. — In  Chap.  I  the  various  types  of 
excavators,  which  may  be  classed  as  competitors,  were  briefly 
described  and  their  fields  of  usefulness  were  outlined  Among 
these  was  mentioned  the  dragline  excavator.  It  is  a  rare  case 
where  the  dragline  is  able  to  compete  successfully  with  the  large 
revolving  shovel  for  ordinary  stripping  purposes.  For  some 
work,  as  stated,  the  dragline  is  better  adapted,  but  for  stripping, 
the  large  shovels  with  long  booms  are  usually  superior.  The 
large  revolving  shovels  are  built  so  that  they  can  be  converted 
into  the  dragline  machines  by  making  a  few  alterations,  thus 
making  them  suitable  for  both  kinds  of  work. 

Cost  of  Shovels. — The  following  will  give  a  general  idea  of 
the  cost  of  shovel  equipment  early  in  1917,  (f.o.b.  eastern 
factories) . 

Standard  Railroad  Shovels. — The  prices  below  cover  machines 
on  standard  mounting,  that  is,  railroad  trucks  under  shovels. 


52 


STEAM  SHOVEL  MINING 


The  prices  for  electric  machines  are  for  motors  operating  on 
3  phase,  60  cycle,  440  volt  alternating-current.  For  other  types 
of  alternating-current  there  is  an  additional  charge  of  about  3 
to  4  per  cent.,  and  for  machines  operated  by  direct-current 
motors,  an  additional  charge  of  about  5  per  cent. 


Domestic 
shipping  weight, 
Ib. 

Working 
weight,  Ib. 

Standard 
dipper, 
cu.  yd. 

Rated 
capacity 
in  cu.  yd. 
per  hr. 

Approximate  cost 

Steam 

Electric 

48,000 

54,000 

N 

30  to  90 

$8,000 

81,000 

95,000 

IK 

60  to  180 

10,200 

118,000 

139,000 

2 

80  to  140 

13,000 

141,000 

166,000 

m 

100  to  300 

14,300 

$22,000 

160,000 

188,000 

3X 

120  to  350 

16,100 

25,500 

188,000 

220,000 

4 

150  to  400 

18,200 

28,500 

210,000 

246,000 

5 

200  to  500 

19,700 

30,750 

235,000 

276,000 

6 

250  to  550 

21,500 

34,500 

Large  Revolving  Shovels. — The  prices  of  these  large  stripping 
shovels,  steam  driven,  ranges  from  $23,000  to  $55,000  according 
to  their  size  and  weight.  Their  shipping  weight  runs  from  250,- 
000  Ib.  to  500,000  Ib.  The  largest  of  these,  when  electric 
driven,  costs  about  $67,600. 

Dragline  Excavators. — The  prices  below  cover  machines  with 
standard  mounting,  that  is  skids  and  rollers,  under  all  except 
the  last  one,  which  is  mounted  on  propelling  equalizing  trucks. 

The  electric  machines  are  for  the  same  class  of  current  as  given 
for  the  shovels,  and  changes  in  current  specifications  add  to 
the  prices  in  the  same  way. 


Domestic 

Standard 

Standard 

Diameter 

Approximate  cost 

shipping 

boom 

bucket 

turntable, 

weight, 

length,  ft. 

.   capacity, 

ft. 

tons 

cu.  yd. 

Steam 

Electric 

35* 

45 

m 

9K 

$10,000 

$13,000 

55* 

60 

2 

14 

13,750 

17,250 

93* 

85 

2« 

20 

20,350 

24,000 

112# 

100 

3K 

24 

25,850 

30,000 

18C# 

125 

3M 

24 

36,850 

43,175 

Including  counterweight. 


MECHANICAL  EQUIPMENT  53 

The  combination  shovel-dragline  machines  cost  a  little  more 
than  the  draglines. 

Light  Shovels. — The  Thew  shovel,  type  0,  weighs  36,000  lb., 
carries  a  %-cu.  yd.  dipper  and  has  a  rated  capacity  of  40  to  50 
cu.  yd.  per  hour.  Equipped  with  steam  power  it  sold  for  about 
$4950,  with  gasoline  power  for  about  $5050. 

LOCOMOTIVES     ] 

General  Governing  Condition. — On  all  large  excavations, 
traction  by  animal  power  has  been  replaced,  where  possible, 
by  mechanical  power.  In  some  cases  where  a  gradual  approach 
is  not  possible,  or  where  the  pit  is  so  deep  that  hauling  on  gradients 
is  not  economical,  inclined  planes  with  hoists  are  provided; 
in  other  cases  material  may  be  hoisted  through  vertical  shafts 
placed  outside  of,  but  connected  by  adits  with  the  pit  area. 
For  the  great  majority  of  open-pit  workings,  however,  some 
class  of  locomotive  is  employed  to  haul  trains  out  over  graded 
road-beds. 

The  selection  of  locomotives  for  such  service  is  governed  by 
the  class  of  power  or  fuel  adopted :  by  the  length,  gauge,  grades 
and  curvature  of  the  track;  and  by  the  weight  of  trains  and 
output  requirements.  Modern  practice  is  constantly  toward 
heavier  and  more  efficient  units  and  it  is  always  desirable  to 
provide  a  reasonable  amount  of  surplus  power,  so  that  the  loco- 
motive will  not  constantly  be  worked  to  full  capacity.  Re- 
serve power  is  economical  because  it  reduces  repair  costs,  fuel 
and  oil,  lengthens  the  working  life  of  the  motive  power  and  pro- 
vides a  reasonable  reserve  for  emergencies. 

It  pays  well  to  buy  locomotives  of  proper  design  to  meet 
requirements  and  to  keep  them  in  good  order.  In  such  service 
as  mining,  where  the  track  must  be  frequently  shifted,  ideal 
conditions  are  generally  impractical,  but  bad  grades,  sharp 
curves,  neglected  road-bed  and  track  and  run-down  rolling- 
stock  should  be  thoughtfully  studied  and  avoided  wherever 
practicable. 

The  majority  of  locomotives  now  in  this  service  are  steam- 
driven  and  coal-fired,  though  wood  or  oil  may  be  substituted. 
Most  of  these  are  of  the  rod  or  direct-acting  type,  either  with 
water-tank  and  fuel-bunker  mounted  on  the  locomotive,  or 
trailed  on  a  tender.  For  heavier  grades  than  are  negotiable 


54  STEAM  SHOVEL  MINING 

with  rod  locomotives  the  Shay  or  Hesler  type  of  geared  locomo- 
tives is  sometimes  employed.  It  should  be  remembered,  how- 
ever, that  in  theory  geared  locomotives  can  haul  no  heavier 
trains  nor  climb  steeper  grades  than  direct-acting  locomotives 
of  the  same  weight  with  all  of  their  weight  on  the  driving  wheels, 
and  carrying  no  separate  tenders.  In  other  words,  considering 
a  locomotive  of  each  of  these  types,  both  having  the  same  weight 
on  the  driving  wheels,  and  both  properly  designed,  they  will 
start  the  same  loads,  because  the  rail  adhesion  is  the  limiting 
factor  in  both  cases.  It  is  a  fact,  however,  that  the  direct- 
acting  locomotive  has  more  tendency  to  slip  its  wheels  in  start- 
ing trains  because  of  the  position  of  the  crank-pins.  On  the 
other  hand,  the  geared  locomotive  will  make  less  mileage  and 
handle  less  tonnage  per  day,  and  has  less  advantage  from  train 
momentum  in  overcoming  grades  because  of  its  speed  and  motion. 
The  torque  of  the  geared  machine  is  more  even  and  better  dis- 
tributed in  starting,  but  the  introduction  of  the  gearing  is  in 
other  ways  a  disadvantage. 

Compressed  air  and  electric  locomotives  are  used  in  some 
places  and  will  be  described  later. 

Direct-connected  Steam  Type. — As  previously  mentioned, 
the  majority  of  locomotives  now  employed  in  open-pit  mining 
is  of  this  type. 

Compounding  permits  the  steam  to  expand  through  a  greater 
range  of  pressure  than  is  possible  in  a  single  cylinder,  and  also 
reduces  the  amount  of  temperature  change  and  consequent 
condensation  in.  each  cylinder,  thus  economizing  fuel.  But  in 
this  class  of  equipment  it  is  not  often  resorted  to. 

Superheating  is  another  method  used  to  avoid  cylinder  con- 
densation with  its  loss  in  efficiency.  By  superheating  steam 
with  a  fire-tube  superheater,  the  steam  is  ordinarily  raised  about 
200°F.  above  the  temperature  of  saturation,  and  in  this  state 
condensaton  in  the  cylinders  is  not  only  largely  avoided,  but 
there  is  also  another  gain  in  efficiency,  because  the  volume  per 
pound  of  superheated  steam  is  greater  than  that  of  saturated 
steam  at  the  same  pressure,  and  hence  each  pound  of  water  evap- 
orated forms  a  larger  volume  of  steam,  'which  means  that  fewer 
pounds  of  steam  are  required  to  fill  the  cylinders. 

The  economies  resulting  from  compounding  or  superheating 
are  best  realized  in  locomotives  working  at  high  power  for  sus- 
tained periods  of  time,  such  as  on  long  heavy  mountain  grades 


MECHANICAL  EQUIPMENT  55 

As  these  conditions  are  not  usual  in  open-pit  work,  the  single 
expansion  locomotive  without  superheater  is  generally  considered 
best.  It  is  therefore  in  this  class  of  engine  that  we  are  interested 
in  the  following  discussion. 

Determination  of  Tractive  Force. — The  hauling  capacity  of  a 
locomotive  is  determined  by  the  relation  between  the  tractive 
force  developed  and  the  resistance  of  the  train,  and  both  of 
these  factors  are  dependent  on  the  speed.  At  starting  speeds, 
a  locomotive  will  usually  develop  at  the  rims  of  the  driving 
wheels  its  rated  tractive  force.  This  is  calculated  from  the  di- 
mensions of  the  engine  by  the  following  formula '} 

LX  0.85P 


T  = 


I) 


Where  T  =  the  rated  tractive  force  at  rim  of  drivers  in  pounds. 
C  =  the  diameter  of 'the  cylinders  in  inches. 
L  =  the  length  of  stroke  of  the  pistons  in  inches. 
P  =  the  boiler  pressure  in  pounds  per  square  inch. 
D  =  the  diameter  of  the  driving-wheels  in  inches. 

0.85  =  85  per  cent  of  the  boiler  pressure  in  pounds  per  square 
inch.  (From  tests  made,  it  has  been  found  that  well  designed 
locomotives  lose  about  15  per  cent,  on  account  of  drop  of  steam 
pressure  between  boiler  and  cylinders,  due  to  condensation  of 
steam,  to  leakage  and  to  internal  friction  of  the  locomotive 
machinery.  This  is  when  the  machine  is  working  at  full-stroke 
and  at  a  speed  not  in  excess  of  the  speed  at  which  it  can  haul 
its  heaviest  load). 

Factor  of  Adhesion. — The  factor  of  adhesion  of  a  locomotive 
is  the  ratio  between  the  working  order  weight  on  the  driving- 
wheels  and  the  tractive  force,  and  hence  is  found  by  dividing 
the  weight  on  the  driving-wheels  by  the  tractive  force.  If 
this  factor  is  too  high  the  locomotive  cannot  slip  its  driving- 
wheels  and  is  called  "logy,"  and  if  the  factor  is  too  low,  the 
driving-wheels  will  slip  too  easily  and  the  engine  will  be  called 
"slippery."  For  saddle-tank  locomotives  carrying  water  and 
fuel  wholly  or  partly  over  the  driving-wheels,  this  factor  should 
be  figured  on  the  basis  of  the  tank  and  bunker  being  only  about 
half  full.  In  a  well  designed  locomotive  the  cylinders  will  be 
so  proportioned  that  there  will  be  sufficient  power  to  just  over- 

1  Most  locomotive  builders  will  supply  Tractive  Force  Tables  covering 
their  product. 


56  STEAM  SHOVEL  MINING 

come  the  adhesion  on  good  clean  dry  rails.  For  this  class  of 
service  the  factor  of  adhesion  may  be  taken  at  from  4.70  to  4.80. 

Draw-Bar  Pull.  —  The  draw-bar  pull  of  a  locomotive  is  simply 
the  tractive  force  minus  the  power  required  to  move  the  locomo- 
tive itself.  It  is  the  net  power  available  for  pulling  the  load 
attached  to  the  locomotive,  and  is  a  variable  quantity  because 
the  amount  of  power  required  to  move  the  locomotive  itself, 
under  different  conditions  of  grade  and  track,  is  variable. 

Resistance  due  to  Grades.  —  When  a  train  is  hauled  up-grade, 
there  is  the  resistance  due  to  lifting  the  train  against  gravity. 
When  the  grade  is  stated  in  per  cent  (or  number  of  feet  rise  per 
hundred  feet  of  haul),  this  resistance  equals  20  Ib.  per  ton  of 
2000  Ib.  for  each  per  cent.  If  the  grade  is  stated  in  feet  per 
mile,  the  resistance  per  ton  of  2000  Ib.  will  be  0.3788  Ib.  per  foot 
of  rise  per  mile.  Grades  generally  account  for  the  greatest 
percentage  of  the  total  resistance. 

Resistance  due  to  Rolling  Friction  —  The  resistance  due  to  roll- 
ing friction,  or  coefficient  of  rolling  friction,  varies  greatly  with 
the  character  and  condition  of  the  rolling-stock  and  track. 
Poorly  laid  track  and  crooked  rails  increase  the  resistance  in- 
definitely. The  resistance  is  increased  by  overloading  the  cars, 
although  the  resistance  per  ton  hauled  is  less  for  properly  loaded 
cars  than  for  empties.  In  cold  weather  the  resistance  is  greater. 
Much  care  should  be  given  to  lubrication  in  all  seasons.  It 
may  be  taken,  however,  that  the  following  resistances  per  ton 
of  2000  pounds  will  be  about  averages. 


With  extra  good  cars  and  track  .................  .  5  to  6j^  pounds 

For  reasonably  good  conditions  ...................  8  to  12  pounds 

For  bad  cars  and  track  ..........................  20  to  40  pounds 

For  hard-running  cars  and  very  rough  track  ........  60  to  80  pounds  plus. 

For  cars  with  wheels  fast  on  axles  and  suitable  bearings  and 
oil-boxes  such  as  are  used  in  pit  service,  this  resistance  should 
not  exceed  8  to  12  pounds,  and  10  pounds  may  be  taken  as  a 
general  average.  This  is  equivalent  to  a  grade  of  0.5  per  cent. 
i.e.  a  car,  once  started,  that  will  just  keep  in  motion  on  a  0.5  per 
cent,  down-grade  would  have  such  a  resistance.  From  this  it 
will  be  seen  that  poorly  built  cars  and  bad  track  are  costly  to 
contend  with. 

It  should  be  mentioned  that  this  resistance  is  not  constant 
but  varies  with  the  speed,  acceleration  and  weight  of  the  cars 


MECHANICAL  EQUIPMENT  57 

hauled;  however  the  foregoing  assumptions  will  be  approximately 
correct  for  this  class  of  work. 

Resistance  due  to  Curves. — A  curve  is  said  to  have  a  radius  of 
so  many  feet,  or  degrees.  By  the  former  is  meant  that  the 
center  line  of  the  track  is  described  as  an  arc  of  a  circle  having 
a  radius  of  so  many  feet;  the  latter  expresses  the  angular  deflec- 
tion from  the  tangent  measured  at  stations  100  ft  apart;  i.e. 
the  number  of  degrees  of  central  angle  subtended  by  a  chord  of 
100  feet  represents  the  "degree**turve".  As  one  degree  of  cur- 
vature is  equal  to  a  radius  of  57BO  feet,  the  number  of  degrees 
divided  into  5730  gives  the  radius  in  feet;  or  the  number  of  feet 
radius  divided  into  5730  gives  the  number  of  degrees.  This 
rule  is  sufficiently  accurate  for  curves  up  to  15  degrees. 

The  resistance  due  to  curves  is  considerable  but  extremely 
variable.  The  shorter  the  radius,  the  longer  the  wheel-bases 
of  the  locomotive  and  cars,  the  greater  the  speed,  the  greater  the 
length  of  the  train  on  the  curve  and  the  greater  the  length  of  the 
curved  track,  the  greater  will  this  resistance  be.  The  eleva- 
tion of  the  outer  rail,  the  condition  of  the  track  and  rolling  stock, 
the  weight  of  the  cars  and  the  proper  widening  of  the  track 
gauge  to  prevent  the  wheels  from  binding  against  the  rails  are 
other  factors  which  enter  into  this  resistance.  Excessive  or 
irregular  curves,  and  very  sharp  curves,  especially  on  steep 
grades,  are  obviously  to  be  avoided  if  the  locomotive  is  to  pull 
efficiently  and  if  wear  and  tear  on  the  track  and  rolling  stock  is 
to  be  kept  down. 

It  is  generally  assumed  that  this  resistance  amounts  to  from 
0.7  to  1.0  pound  per  ton  per  degree  of  curvature,  the  lower  figure 
being  used  for  large  capacity  cars  and  the  higher  figure  for  small 
capacity  cars,  as  in  the  latter  case  there  are  more  wheels  per 
ton  of  weight  than  in  the  former. 

Because  of  this  resistance  it  is  customary,  when  a  curve  occurs 
on  a  grade,  to  reduce  the  grade  of  the  curved  part  of  the  track 
so  that  the  combined  resistance  of  the  lighter  grade  and  curve 
will  not  exceed  the  resistance  of  the  heavier  grade  on  the  straight 
part  of  the  track.  This  is  called  compensation  and  many  roads 
allow  0.035  per  cent  in  grade  for  each  degree  of  curve.  For 
sharp  curves  and  long  wheel-bases  this  may  be  increased  to  0.05 
per  cent  per  degree.  This  resistance  is  usually  nearly  twice  as 
great  for  the  locomotive  as  for  the  cars  because  of  the  longer 
wheel  base  of  the  former. 


58  STEAM  SHOVEL  MINING 

To  reduce  binding,  the  usual  amount  of  clearance  between  the 
rail  and  wheel  flanges  is  increased  on  curves.  On  curves  up  to 
eight  degrees  widening  may  be  omitted, but  for  each  two  de- 
grees or  fraction  there  of  over  eight  degrees,  the  gauge  should 
be  widened  3^  inch  until  a  maximum  of  4  feet  9J4  inches  is 
reached  for  standard  gauge  tracks. 

Elevating  the  outer  rail  on  curves  is  desirable  to  counteract 
the  centrifugal  force  tending  to  tip  over  the  rolling  stock.  It 
is  customary  to  elevate  the  outer  rail  about  J^  inch  per  degree 
of  curvature  for  train  speeds  of  25  to  35  miles  per  hour,  but  this 
elevation  should  not  exceed,  say,  eight  inches. 

Hauling  Capacity  of  Locomotives. — From  the  foregoing  can  be 
determined  the  hauling  capacity  of  any  locomotive,  as  it  is 
simply  the  tractive  force  of  the  locomotive  divided  by  the  sum 
of  the  resistances  due  to  gravity,  rolling  fiction  and  curvature, 
minus  the  weight  of  the  engine  (and  tender,  if  any).  Expressed 
as  a  formula  this  is : 

H = STTTFc ~  E 

Where  H  =  the  hauling  capacity  in  tons  of  2000  Ibs. 

T  =  the  tractive  force  of  the  locomotive  in  pounds. 
G  =  the  resistance  of  gravity  in  pounds  per  ton. 
R  =  the  resistance  of  rolling  friction  in  pounds  per  ton 
C  =  the  resistance  of  curvature  friction  in  pounds  per  ton 
E  =  the  weight  of  the  locomotive  in  tons. 

Example. — What  is  the  hauling  capacity  of  a  saddle-tank 
locomotive  weighing  65  tons,  with  tank  and  bunker  half  full, 
all  the  weight  on  the  six  driving  wheels,  cylinders  18  inches  in 
diameter  with  24-inch  stroke,  driving  wheels  44  inches  in  dia- 
meter, boiler  pressure  175  Ibs.  per  sq.  in.,  operating  on  a  3  per 
cent,  grade,  10°  curve,  and  rolling  friction  of  cars  10  pounds  per 
ton. 

Substituting  in  .the  formula  for   Tractive   Force,    we   have 

T  =  182  X  24  *  °'85  X  175  =  26,288  Ibs. 
44 

Assuming  a  factor  of  adhesion  of  4.7  gives  a  force  of  adhesion 
of 

130,000  Ibs.      --  _Kft 

j       =  27,659  pounds. 


MECHANICAL  EQUIPMENT  59 

The  locomotive  will  therefore  be  able  to  exert  its  full  tractive 
force  before  slipping.     In  the  formula  for  hauling  capacity 

G  will  equal  60  pounds 
R  will  equal  10  pounds 

C  will  equal,  say,  0.8  pounds  X  10,  or  8  pounds. 
E  will  be  65  tons 
Then 


2fi 

H  =    n      '—  --  -  —  65  =  272  tons  as  the  hauling  capacity. 
bU  -j-  1U  -j-  o 

Further,  if  it  be  assumed  that  the  load  is  to  consist  of  loaded 
cars,  weighing  20  tons  each  and  carrying  50  tons  of  material 
or  a  total  weight  of  70  tons,  this  locomotive  should  start 

070 

y0   =  3.88  loads. 

If  the  rolling  friction  resistance  rate  is  assumed  to  be  greater 
for  the  locomotive  than  that  assumed  for  the  cars,  (as  is  usually 
the  case),  then  the  hauling  capacity  may  be  computed  by  first 
deducting  from  the  tractive  force  the  total  resistance  to  be 
overcome  by  the  locomotive  in  handling  itself  under  the  above 
conditions  and  then  dividing  the  remainder,  or  draw-bar  pull, 
by  the  sum  of  the  rates  of  the  various  resistances  assumed  'for 
the  cars. 

It  will  be  noted  that  the  foregoing  is  really  the  starting  load, 
since  it  takes  no  account  of  the  speed  at  which  the  load  is  to 
be  hauled,  and  as  the  prolonged  tractive  force  depends  on  the 
speed  and  heating  surface  of  the  boiler,  this  would  have  to  be 
modified  for  a  prolonged  effort  at  moderate  speed.  At  15  miles 
per  hour  probably  only  85  per  cent,  of  the  starting  tractive  effort 
could  be  maintained  for  any  considerable  length  of  time,  but  for 
short  hauls  it  would  not  be  reduced  more  than  a  few  per  cent. 
and  should  haul  any  load  it  can  start. 

Under  actual  working  test  it  was  found  that  this  locomotive 
would  pull  four  of  these  cars  up  a  3  per  cent,  grade  and  two  up  a 
4  per  cent,  grade,  though  by  double-heading,  two  of  these  loco- 
motives would  pull  five  loads  up  a  4  per  cent,  grade.  Part  of 
the  track  was  on  about  10°  curves,  and  the  speed  of  the  trains 
was  from  8  to  10  miles  an  hour  at  the  beginning  of  the  grade. 
On  account  of  the  drop  in  boiler  pressure  under  this  pull,  the 
locomotives  could  only  handle  these  loads  for  a  distance  of 
from  800  to  1000  feet. 


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MECHANICAL  EQUIPMENT 


63 


The  chart,  Fig.  14,  graphically  shows  how  the  hauling 
ability  of  a  locomotive  varies  under  variable  conditions  of  grade 
and  curvature  of  track.  For  example,  on  straight  track  and  4 
per  cent,  grade,  its  hauling  ability  for  the  entire  train,  is  but  11 
per  cent,  of  that  on  straight  level  track;  on  level  track  and 
20°  curve  its  ability  is  but  33  per  cent. ;  on  4  per  cent,  grade  and 
20°  curve  its  ability  is  but  9  per  cent. 

Table  101  is  here  reproduced  as  a  handy  reference  in  selecting 
locomotives  of  suitable  weight  to  do  any  given  work.  It  also 
shows  the  effect  of  grade  and  train  resistance. 


A-S>traightTrackon  Variable  Grade 
8- Level  Track  on  Variable  Curvature 
C-  Track  on  Varfabfe  Grade  and  Curvature 


0  Grade    I  PerCent  2 
0  Curve     5  Degree    10 

FIG.   14. — Hauling  capacity  of  locomotives. 

Horse-power. — There  are  times  when  it  is  useful  to  know  the 
h.p.  of  a  locomotive,  though  generally  this  is  not  of  great  signi- 
ficance. Since  one  h.p.  is  the  ability  to  lift  one  Ib.  against  gravity 
33,000  ft.  in  one  minute,  then 

TXS 


HP  = 


375 


Where  HP  represents  the  h.p.  of  the  locomotive, 
T    represents  the  tractive  force  in  pounds, 
S     represents  the  speed  in  miles  per  hour  at  which 
the    locomotive    can    haul    its    heaviest    load. 
S  may  be  determined  from  the  following  formula: 


.  K,  Porter  Co,—  12th  edition  catalogue,  p.  105. 


64 


STEAM  SHOVEL  MINING 


Where  D  represents  the  diameter  of  driving  wheel  in  inches, 
F    represents  a  factor  taken  from  the  table  below, 


Stroke  in  inches  .  .  . 
Factor 

8 
5 

10 
5  2 

12 

5  4 

14 
5  6 

16 

5  8 

18 
6 

20 
6  2 

22 
6  4 

24 
6.6 

26 

6.8 

28 

7 

Thus,  in  case  of  the  65-ton  engine  mentioned 

44 
S  =  -^  =  7.33  miles  per  hour,  and 

26,288  X  7.33 
HP  =  -    —        ~        =513  horse  power 


The  boiler  h.p.  is  dependent  on  many  factors  of  heating, 
but  with  good  bituminous  coal,  3  sq.  ft.  (with  oil,  2  sq.  ft.) 
of  heating  surface  will  ordinarily  create  steam  for  one  h.p., 
provided  there  is  at  least  1  sq.  ft.  of  grate  area  for  every  60  sq. 
ft.  of  heating  surface. 

Fuel  and  Water  Consumption.  —  A  locomotive  will  ordinarily 
consume  about  4  Ibs.  of  coal  and  30  Ib.  of  water  per  horse-power 
hour.  The  quantity  of  water  required  (in  gallons)  for  a  run 
of  one  mile  about  equals  the  average  resistance  (in  pounds) 
overcome,  divided  by  104  or,  say,  one  per  cent,  of  the  resistance 
to  be  overcome.  As  approximately  one  gallon  of  water  is 
evaporated  by  one  pound  of  good  coal,  the  foregoing  answer 
also  represents  the  pounds  of  coal  consumed.  Under  poorer 
conditions  1.6  pounds  of  coal  are  sometimes  required  per  gallon 
of  water  evaporated.  Short  runs  and  intermittent  service 
increase  both  the  coal  and  water  consumption  per  mile.  Good 
coal  will  liberate  about  14,000  B.t.u.  per  pound  while  poor  coal 
may  run  below  10,000  B.t.u.;  fuel  oil  will  give  about  19,000 
B.t.u.  per  pound.  (This  runs  about  7.6  Ib.  per  gallon  and  42 
gal.  or  319.2  Ib.  per  barrel  for  crude  petroleum).  Wood  fuel 
averages  about  5500  B.t.u.  per  pound  under  ordinary  conditions. 

Usual  Sizes  for  Open-pit  Work.  —  Some  contractors  use  four- 
wheel  locomotives  with  cylinders  as  small  as  5  in.  X  10  in.  and 
weighing  only  about  5  tons,  but  for  general  use  in  and  around 
shovel  mines  locomotives  are  seldom  lighter  than  35  tons  with 
cylinders  14  in.  X  18  in.  The  heavier  four-wheel  connected 
saddle-tank  engines  run  up  to  60  tons  and  have  cylinders  18  in. 
X  24  in. 

Six-wheel  connected  saddle-tank  locomotives  range  from  7-ton, 


MECHANICAL  EQUIPMENT  65 

with  6  in.  X  10  in.  cylinders,  to  85-ton  machines  with  21  in. 
X  26  in.  cylinders.  The  heavier  types,  say,  from  50  tons  with 
16  in.  X  24  in.  cylinders  up,  are  preferred  where  practicable,  for 
although  they  require  heavier  and  better  track,  they  haul  heavier 
loads  and  are  more  economical  in  labor  and  operating  costs  per 
ton  mile.  As  they  carry  about  3  tons  of  coal  and  2000  gal.  of 
water  they  are  good  for  a  haul  of  several  miles.1  Side-tanks 
may  be  substituted  for  saddle-tanks  but  the  latter  are  usually 
preferred.  A  two-wheel  truck  may  be  added  either  forward 
or  back,  or  both  forward  and  back,  of  the  drivers  to  carry 
overhang  or  assist  in  rounding  curves.  These  locomotives 
are  built  for  moderate  speeds  and  are  very  satisfactory  where 
the  run  is  not  long  enough  to  require  a  separate  tender.  In 
the  iron  mines  of  the  Mesabi,  locomotives  with  cylinders 
19  in.  X  26  in.  and  20.  in  X  26  in.  with  separate  tenders  are 
in  general  use.  They  seldom  operate  on  grades  over  2  per 
cent.  They  are  equipped  with  8^  in.  X  10J^  in.  cross  com- 
pound air  pumps  for  operating  the  air  dump  cars;  also  with  two 
camel-backs,  a  piece  of  1J^  in.  hoisting  chain  and  20  ft.  of  1  in. 
chain  for  replacing  cars  and  locomotives  on  the  track.  Present 
practice  generally  calls  for  standard  gauge,  viz.,  4  ft.  8J^  in- 
Such  companies  as  the  Baldwin  Locomotive  Works,  American 
Locomotive  Company,  H.  K.  Porter  Company  and  others 
manufacture  these  locomotives  and  are  glad  to  furnish  specifica- 
tions and  advice  on  selection,  but  it  is  advisable  to  have  same 
carefully  passed  upon  by  someone  competent  to  judge  and  fami- 
liar with  the  local  conditions  of  service  for  which  they  are  to  be 
used.  It  is  not  the  purpose  of  this  work  to  consider  such  items 
of  equipment  in  minute  mechanical  detail  as  too  much  space 
would  be  required. 

Cost  of  Locomotives. — Recent  quotations  on  the  cost  of  loco- 
motives delivered  at  the  point  of  manufacture  seem  to  be  from 
about  9  cents  to  10  cents  per  pound.  Thus  a  locomotive  with 
cylinders  19  in.  X  26  in.,  six  46  in.  driving-wheels  and  a  two- 
wheeled  forward 'truck,  burning  coal,  and  with  iron  flues,  steel 
tires,  two  feed-water  injectors  and  a  2200  gallon  tank  on  boiler 

irThe  consumption  of  supplies  per  9  hr.  shift,  for  65-ton  locomotives 
of  this  class  has  been  found  to  average  about  as  follows:  coal,  3^  tons; 
cylinder  oil,  5  pints;  engine  oil,  4  pints;  kerosene,  2  pints;  cup  grease,  J^lb.; 
cotton  waste,  %  lb.;  calcium  carbide  for  night  illumination,  8  Ibs.;  water, 
6,000  gallons. 


66  STEAM  SHOVEL  MINING 

is  quoted  at  $15,380  at  Philadelphia.  Former  prices  have  ranged 
from  7J<2  cents  per  pound  for  100-ton  engines  to  about  9  cents 
per  pound  for  50-ton  engines.  The  builders  are  always  glad 
to  furnish  full  specifications  and  prices  to  prospective  buyers. 

Geared  Types. — If  pit  grades  and  approaches  cannot  be  kept 
down,  to,  say  4  per  cent  or  under,  rod  locomotives  will  operate 
only  at  great  inefficiency.  Under  such  conditions  it  may  be 
better  to  substitute  geared  locomotives  of  the  Shay  or  Hesler 
type,  or  even  a  rack  type.  These  machines  have  the  greatest 
tractive  power,  consistent  with  their  weight,  of  any  locomotive 
and  tender.  They  are  better  adapted  to  heavy  grades,  sharp 
curves,  temporary  track  and  light  rail  than  the  rod  type.  Due 
to  the  greater  number  of  cylinder  reciprocations  they  exert  a 
steadier  pull  and  give  lower  fuel  combustion.  They  can  move 
at  slower  speeds  and  can  start  loads  without  danger  of  stalling 
It  will  be  noted  that  all  of  the  weight  of  engine  and  tender  is  on 
the  drivers,  and  that  these  consist  of  trucks  of  short  wheel  base 
which  are  free  to  swivel,  enabling  the  engine  to  pass  sharp  curves 
with  the  least  possible  friction  and  strains  to  track  alignment. 
They  are  not  adaptable  to  speeds  of  over,  say,  15  to  20  miles 
per  hour  and  the  repairs  and  maintenance  are  generally  high. 

The  Shay  locomotives,  built  by  the  Lima  Locomotive  Works, 
of  Lima,  Ohio,  and  the  Hesler  locomotives  have  been  used  in  some 
of  the  open-pit  mines  on  the  iron  ranges,  and  at  other  places. 

Where  grades  of  over,  say,  7  per  cent,  would  be  unavoidable 
some  means  of  hoisting  on  inclined  plane  or  through  shafts  must 
be  resorted  to  for  handling  heavy  tonnages.  In  a  few  instances 
cableways  have  been  installed,  but  owing  to  the  necessity  of 
track  shifting  and  their  lower  capacity  they  are  rare. 

Compressed  Air  Locomotives. — General  Considerations — Com- 
pressed air  haulage  is  often  employed  in  underground  mines, 
but  seldom  if  ever  in  open-pit  workings.  Where  mines  are  dusty 
or  gaseous,  as  in  some  coal  seams,  or  where  ventilation  is  poor, 
or  the  workings  wet  or  heavily  timbered,  or  the  roof  bad,  or  where 
accident  by  electric  shock  would  be  serious,  compressed  air 
locomotives  are  of  marked  advantage,  but  in  open-pit  mines 
these  conditions  are  not  met.  A  few  remarks  regarding  them, 
however,  will  probably  be  of  interest.  The  two-stage  compressed- 
air  locomotive  with  an  atmospheric  interheater  located  between 
high  and  low  pressure  cylinders  has  shown  such  increased 
efficiency  over  the  single-expansion  locomotive  that  it  is  much 


MECHANICAL  EQUIPMENT  67 

preferred.  Comparative  working  tests  show  a  gain  in  efficiency 
of  over  50  per  cent,  and  a  saving  in  compressed  air  consumed 
of  over  30  per  cent.  The  air  is  charged  into  the  main  reservoir 
at  a  pressure  of  700  to  1200  pounds  per  square  inch;  it  then 
passes  through  a  reducing  valve  which  maintains  a  constant 
pressure  of  250  pounds  in  the  auxiliary  reservoir;  from  here 
it  is  fed  to  the  high  pressure  cylinder  and  partially  expanded 
to  about  50  pounds  pressure,  becoming  much  colder  than  the 
surrounding  atmosphere;  it  is  then  passed  through  a  tubular 
interheater  in  which  it  is  heated  to  nearly  atmospheric  tempera- 
ture by  contact  with  the  surrounding  air ;  the  expansion  is  then 
completed  in  the  low-pressure  cyinder.  In  practice  approxi- 
mately equal  amounts  of  work  are  thus  done  between  250  pounds 
and  50  pounds  pressure,  and  between  50  pounds  and  atmospheric 
pressure. 

Besides  the  compressed-air  locomotives,  there  must  be  pro- 
vided charging  stations  at  convenient  points,  each  station  con- 
sisting of  valve,  bleeder  valve  and  flexible  metallic  coupling. 
These  serve  for  connecting  the  locomotive  with  the  air  supply, 
and,  when  properly  arranged,  permit  the  locomotive  to  be 
stopped,  charged  and  restarted  inside  of  a  minute  and  a  half. 

Next  there  is  provided  stationary  storage  to  permit  the  rapid 
charging  of  the  locomotives  and  the  continuous  operation  of  the 
compressor.  This  storage  is  of  such  capacity  that  the  locomotive 
can  be  charged  without  material  reduction  in  pressure.  If  the 
stations  are  some  distance  from  the  compressor,  it  is  usually 
best  and  most  economical  to  take  care  of  this  capacity  by  using 
pipe  of  sufficient  size  to  give  the  required  volume,  rather  than  a 
combination  of  pipe  of  smaller  diameter  and  storage  tanks. 

Lastly  there  is  the  compressor,  which  usually  compresses 
air  to  about  1000  Ib.  per  sq.  in.  A  high  pressure  is  required  to 
store  sufficient  quantity  of  air  in  the  locomotive  to  drive  it  the 
necessary  distance  without  recharging  and  not  have  the  reservoirs 
excessively  large.  The  size  of  the  compressor  depends  upon  the 
quantity  of  free  air  which  must  be  compressed  to  do  the  total 
amount  of  work  in  a  given  period.  A  thorough  investigation 
of  the  work  to  be  performed  by  the  locomotives  is  needed  to 
determine  the  proper  size. 

This  layout  complete  usually  makes  the  first  cost  of  installa- 
tion of  compressed-air  locomotives  from  two  to  three  times  as 
great  as  for  steam  locomotives,  and  perhaps  about  the  same  as  a 


68  STEAM  SHOVEL  MINING 

complete  trolley-type  electric  locomotive  layout.  Therefore, 
compared  with  steam  locomotives,  one  or  more  of  the  following 
features  must  be  of  sufficient  weight  to  justify  the  additional 
expenditure : 

1.  Absolute  insurance  against  fire  or  explosion  due  to  sparks, 
flame  or  heat  emitted  or  caused  by  locomotives. 

2.  Cleanliness. 

3.  Great  economy  of  power  due  to  central  generation  from 
cheap  fuel,  even  though  at  considerable  distance  from  the  charg- 
ing stations;  or  where  the  compressor  can  be  run  for  a  short 
time  and  the  stationary  storage  built  up  to  run  the  locomotives 
for  some  considerably  longer  period. 

4.  Locomotives  needed  for  instant  service,  or  without  licensed 
engineers. 

5.  Great  saving  in  operating  and  contingent  expenses,  fixed 
charges  and  depreciation,  when  all  are  fairly  considered. 

As  previously  mentioned  it  will  be  an  exceptional  case  indeed 
in  open-pit  work  where  any  of  the  above  features  will  be  essential. 

Compared  with  trolley-type  electric  locomotives,  the  air 
machines  are  safer  from  shock,  do  not  require  trolley  lines  nor 
bonded  rails,  operate  better  in  wet  places  and  have  about  the 
same  operating  power  cost.  They  are  fully  as  reliable  and 
flexible  and  will  meet  all  ordinary  requirements  of  operation  as 
well  as  any  type  of  locomotive  of  the  same  weight. 

Cost  of  Installation  and  Operation  of  Air  Haulage. — As  a 
matter  of  approximate  comparative  interest  the  cost  of  an 
installation,  capable  of  handling  3000  tons  over  a  2  per  cent, 
grade  for  a  distance  of  one  mile  in  9  hr,.  is  estimated: 

2  two-stage  20-ton  compressed  air  locomotives $10,800. 

One  800  cu.  ft.  1000-pound  compressor 9,000. 

One  300  h.p.  boiler  at  $15.00  per  hp 4,500. 

5000  feet  of  5-inch  special  air  line  @  70  cents 3,500. 

3  charging  stations  complete 400. 

Fittings,  valves  and  miscellaneous 800. 

Foundation  and  installation  of  machinery 500. 

Installation  of  pipe  line 600. 


Total : $30,100. 

The  cost  of  operation  of  the  above  plant  per  day  of  9  hr.  is 
estimated  to  be: 


MECHANICAL  EQUIPMENT  (50 

2  locomotive  drivers  @  $4.50 $  9 . 00 

2  brakesmen                @  $4.00 8.00 

Compressor  attendance 4 . 00 

Oil  for  compressor  and  locomotives 1 . 50 

Repairs  for  compressor,  boiler,  locomotives  and  pipe  lines 4 . 00 

Coal,  (4M  Ibs.  per  h.p.-hr.,  say  3000  h.p.hrs.)  @  $5.  per  ton,  say. . .  34.00 

Interest  and  depreciation  @  15  per  cent 12. 50 


Total $73.00 

Moving  3000  tons  one  mile  =  3000  ton  miles 

Cost  per  ton  mile 2.433^ 

Operating  two  shifts  would  show  a  reduction  in  the  above 
cost  by  about  0.3j£  per  ton  mile. 

Electric  Locomotives. — Trolley  System. — Like  compressed-air 
haulage,  electric  locomotives  operated  by  overhead  trolley  lines, 
have  found  a  very  practical  field  in  underground  mines,  but 
are  seldom,  if  ever,  used  in  open-pit  mines.  The  cost  of  in- 
stallation of  such  a  system  would  probably  be  about  as  expensive 
as  compressed-air  and  much  greater  than  for  steam  locomotives. 
Provision  would  have  to  be  made  for  the  trolley  lines  and  bond- 
ing of  rails,  and,  for  work  requiring  much  shifting  of  track,  this 
would  be  a  serious  disadvantage  and  expensive  to  maintain. 
The  principal  advantages  would  be  found  in  cheaper  power 
cost,  elimination  of  firemen  and  somewhat  better  operation  on 
heavy  grades.  The  disadvantages  of  higher  first  cost  of  instal- 
lation and  subsequent  Lmaintenance  bf  overhead  feeders  and 
track  bonding  on  nonpermanent  track  would  in  most  cases 
certainly  be  much  greater  than  the  advantages  gained.  There 
is  also  a  lack  of  flexibility  in  train  movement,  as  the  locomotives 
cannot  operate  (except  for  short  distances  when  supplied  with 
reeled  feeder)  on  lines  not  electrified. 

Centrally  Controlled  Systems 

The  Woodford  System.1 — The  Woodford  system  is  a  centrally 
controlled  electric  haulage  system  which  has  been  installed  in  a 
number  of  shovel  workings  of  the  quarry  type  and  is  giving 
satisfactory  service. 

It  is  described  as  a  system  of  haulage  for  "operating  a  multiplicity 
of  cars  from  a  central  controlling  tower  by  remote  control,  and  is  appli-  • 
cable  to  such  industrial  haulage  as  is  found  in  stone  quarries,  open- 

1  Woodford,  F.  E.  Proceedings  of  the  Engineers'  Society  of  Western 
Pennsylvania,  vol.  31,  p.  583-608,  Sept.  21,  1915. 


70  STEAM  SHOVEL  MINING 

mines,  clay  and  gravel-pits  and  other  places  where  the  distance  is  not 
too  great  and  where  the  operation  of  the  cars  can  be  seen  for  at  least 
part  of  the  time  from  the  controlling  tower. 

"Each  car  carries  its  own  motive  power  and.  control  apparatus,  tak- 
ing current  from  a  sectionalized  third  rail,  which  allows  the  car  to  be 
started  and  stopped,  or  have  brakes  applied  at  the  will  of  the  tower 
operator  and  the  car  to  have  its  direction  reversed  at  certain  fixed  points. 
Control  apparatus  on  the  car  is  arranged  so  that  as  the  car  descends 
grades  the  motors  can  be  connected  across  resistance  banks  and  the 
regenerative  effect  used  for  retardation  purposes. 

"The  third  rail  which  extends  over  the  whole  territory  covered  by 
the  haulage  system,  is  divided  into  long  or  short  sections,  as  conditions 
require,  and  an  independent  feeder  is  extended  from  the  control  tower 
to  each  section.  Tower  operator  has  two  voltages,  250  volts  and  90 
volts,  which  he  can  apply  to  various  sections  of  the  third  rail  at  will. 
250  volts  is  used  for  haulage  purposes  and  90  volts  is  for  braking  pur- 
poses. The  regular  car  rails  are  used  as  a  return  circuit. 

"The  tower  apparatus  consists  of  a  switching  mechanism  by  means  of 
which  the  tower  operator  may  put  haulage  or  braking  voltages  on  sec- 
tions of  third  rail,  or  allow  them  to  stand  without  applied  voltages. 
In  the  tower  machine  there  are  also,  when  desired,  control  switches  for 
operating  motor-driven  track  switches,  reversing  switches  and  other 
special  apparatus  located  at  distant  points  on  haulage  system. 

"Each  car  truck  is  fitted  with  two  railway  type,  250  volt,  direct- 
current  series  motors,  mounted  upon  the  axles  and  supported  by  sus- 
pension springs  and  connected  with  the  axle  through  single  reduction 
gears  in  the  ordinary  manner  adopted  by  electric  traction  practice. 
These  motors  have  their  shafts  extended  at  the  commutator  ends  and 
carry  a  specially  designed  solenoid  brake,  which  is  applied  by  the  action 
of  the  solenoid  and  released  by  springs.  The  car  truck  also  carries 
three  other  pieces  of  apparatus  necessary  for  the  operation  of  the  cars 
from  a  central  point.  They  are  a  bank  of  resistance,  a  double-pole 
double-throw  switch  for  reversing  the  direction  of  the  motors,  and  an 
electric  relay  or  selector  switch.  This  selector  switch  is  a  solenoid- 
operated  switch  having  two  contacts  and  two  positions.  It  is  locked 
in  its  gravity  position  with  one  contact  open  and  one  contact  closed. 
In  its  position  induced  by  the  solenoid  it  is  also  locked,  opening  the 
gravity  circuit  and  closing  the  other  circuit.  The  solenoid  will  not 
respond  to  a  voltage  lower  than  175,  but  after  being  closed  will  hold  in 
with  50  volts,  or  even  less. 

"The  motors  are  operated  with  the  selector  switch  in  its  excited  posi- 
tion. The  circuit  in  the  gravity  position  is  connected  to  the  brake  sole- 
noids, and  the  relay  will  remain  locked  in  gravity  position  while  the 
brakes  are  applied.  While  the  relay  is  in  the  gravity  position  it  also 
establishes  a  circuit  from  the  motors  on  the  car  to  the  bank  of  resistance 


MECHANICAL  EQUIPMENT  71 

which  the  car  carries.  This  resistance  is  adjusted  to/dissipate  the  cur- 
rent generated  by  the  motors  running  as  generators  while  the  car  is 
traveling  down  a  grade  thus  furnishing  a  dynamic  brake  for  the  car  which 
is  not  under  the  control  of  the  operator.  This  feature  forms  a  safety 
device  should  the  circuit  breaker  go  out  while  the  car  is  ascending  the 
grade,  as  upon  circuit  breaker  opening  the  car  will  merely  coast  back 
down  hill  at  a  not  excessive  speed.  While  the  operator  has  control  of 
the  brakes  at  all  times,  this  feature  also  relieves  him  of  governing  or 
speeding  the  car  while  it  is  traveling  down  grade.  This  feature  renders 
the  system  semi-automatic,  arranging  its  operation  so  that  it  is  neces- 
sary for  the  operator  to  give  very  little  attention  to  the  running  of 
the  cars  except  where  they  are  stopped  for  loading  or  unloading.  .  . 
From  the  central  controlling  tower  placed  at  smy  convenient  position, 
we  are  able  to  excite  any  section  of  third  rail  with  a  voltage  ranging 
from  30  to  100  for  controlling  the  brakes,  as  well  as  with  the  starting 
and  running  current  for  the  motors. 

"A  reversing  switch  is  placed  on  the  car  so  that  it  is  operated  by  a 
lever  protuding  from  the  side  of  the  truck  in  such  a  manner  as  to  engage 
track  cams  placed  at  desired  locations  along  the  track.  These  track 
cams  are  stationary  forgings  so  formed  as  to  throw  the  lever  in  the 
proper  position  and  placed  beside  the  track  switch  where  all  the  cars 
are  to  be  reversed.  At  points  along  the  track  whereat  is  necessary  for 
only  part  of  the  cars  to  be  reversed  this  reversing  cam  consists  of  forg- 
ings and  levers  having  two  positions  and  operated  by  a  solenoid.  Should 
it  be  necessary  to  reverse  the  car,  this  solenoid  is  excited  from  the  tower 
by  a  foot  switch.  It  will  readily  be  seen  that  by  this  method  operation 
in  any  manner  to  meet  any  conditions  may  be  accomplished,  and  with 
track  cams  at  the  top  of  all  grades  it  is  impossible  for  a  car  to  enter 
upon  that  grade  without  the  reversing  switch  and  selector  switch  being 
in  the  proper  position  to  cause  motors  to  generate  current  as  they  are 
propelled  by  the  momentum  of  the  car,  and  furnishing  the  dynamic 
brake,  maintaining  a  fixed  speed  at  all  times. 

"At  the  dumping  hopper  or  crusher  another  form  of  reversing  cam 
has  been  adopted,  which  is  thrown  into  different  positions  by  a  motor- 
driven  movement.  This  cam  carries  parallel  bars  some  ten  or  twelve 
feet  in  length  between  which  the  reversing  lever  of  the  car  passes  so 
that  the  car  may  be  spotted  in  any  particular  position  for  dumping, 
arriving  from  either  direction  and  leaving  in  either  direction.  This 
motor-driven  cam  is  also  operated  by  push-button  switches  from  the 
tower. 

"The  elements  described  above  together  with  centrally  controlled, 
electrically  operated  track  switches,  with  which  all  are  familiar,  render 
this  system  of  control  sufficiently  flexible  to  meet  any  and  all  conditions 
and  bring  its  operating  levers  within  the  reach  of  a  single  man.  A  car 
may  be  switched  to  any  track;  may  be  run  into  a  passing  track  from  the 


72  STEAM  SHOVEL  MINING 

main  line;  may  be  stopped  and  started  from  any  point  and,  in  fact, 
operated  in  the  same  manner  as  though  there  were  a  motorman  upon 
each  car. 

"The  design  of  a  car  to  carry  this  apparatus  is  not  materially  dif- 
ferent than  the  standard  construction  of  dump-cars  to  which  in  many 
cases  the  motors  and  other  apparatus  have  been  applied." 

Special  care  has  been  given  the  design  of  the  cars  so  that  they 
may  well  withstand  the  severe  service  of  shovel  loading. 

The  following  advantages  are  claimed  for  the  system: — re- 
duction in  power  cost,  reduction  in  labor  cost  and  decreased 
amount  of  rolling-stock  required.  It  is  stated  that  the  capacity 
of  the  steam-shovel  is  materially  increased  by  supplying  cars 
individually  as  the  shovel  is  not  kept  waiting  between  trains. 
The  power  cost  reduction  is  claimed  by  virtue  of  dispensing  with 
locomotives  and  placing  the  load  on  top  of  the  tractive  machinery. 

The  labor  cost  for  operation  is  reduced  because  the  entire 
system  is  operated  by  a  very  small  crew,  which  may  be  as  low 
as  one  operator  where  only  a  few  shovels  are  involved  and  where 
all  parts  can  be  seen  from  one  point.  A  smaller  amount  of  roll- 
ing-stock is  required  because  locomotives  are  eliminated  and 
cars  need  not  be  tied  up  in  trains  awaiting  loading  and  dumping. 
Each  car  consequently  makes  many  more  trips  than  do  the  cars 
hauled  in  trains.  The  design  of  the  car  units  enables  them  to 
negotiate  curves  much  sharper  and  grades  much  steeper — 10  per 
cent,  and  over — than  can  be  taken  by  locomotives. 

The  .operating  and  upkeep  costs  are  given  at  an  average  of 
not  over  one-half  cent  per  ton  mile,  in  all  except  very  small 
installations;  the  upkeep  of  cars  and  apparatus  being  less  than 
that  of  locomotives,  and  cars  for  an  equal  amount  of  haulage. 
The  elimination  of  water  and  fuel  supply  is  an  advantage. 

"The  installation  cost  compared  with  locomotive  haulage  has  been 
found  to  be  practically  equal  with  a  capacity  of  3000  tons  in  ten  hours. 
For  smaller  capacities  the  installation  cost  of  an  electric  haulage  sys- 
tem has  been  found  to  increase  gradually  above  that  of  locomotive 
haulage,  while  above  3000  tons  capacity  it  has  been  found  to  be  some- 
what less.  This,  of  course,  is  in  cases  of  locomotive  haulage  using  cars 
of  equal  durability  and  equal  weight,  and  while  most  of  the  locomotive 
systems,  in  use  at  the  present  time  are  operating  with  cars  of  lighter 
construction,  the  upkeep  of  these  light  cars  is  very  much  greater." 

An  advantage  noted  is  the  elimination  of  a  certain  risk  to 
men  working  on  the  rock  trains.  This  has  reduced  casualty 


MECHANICAL  EQUIPMENT  73 

insurance  rates  as  well  as  being  commendable.  Another  ad- 
vantage is  in  the  flexibility  of  handling  material  from  end  or 
butt  shovel-cuts,  where  one  car  loading  is  necessary.  The  10- 
cu.  yd.  cars  weigh  net  about  15  tons  and  carry  about  14  tons. 

Some  of  the  companies  using  the  system  are:  The  Casparis 
Stone  Company;  of  Kenneth,  Indiana;  Dolese  and  Shepard 
Company,  Gary,  Illinois;  Hohan  Stone  Company,  Maple  Grove, 
Ohio. 

Mr.  0.  P.  Chamberlain  of  the  Dolese  &  Shepard  Co.  states: 

"1  am  satisfied  as  now  developed  our  rate  of  maintenance  is  lower 
than  for  steam  locomotive  operated  plants.  .  .  Our  current  is  pur- 
chased .  .  .  at  a  cost  averaging  2.65  cents  per  kilowatt  hour." 

Mr.  George  W.  Patnoe  of  the  Hohan  Stone  Co.,  states: 

"We  installed  twenty-five  10-yard  cars  to  supply  a  plant  that  was 
producing  from  600  to  700  tons  per  hour.  We  have  never  used  over 
two-thirds  of  the  equipment." 

At  another  quarry,  he  states:  "We  installed  the  Woodford  system 
with  ten  6-yard  cars.  They  would  be  loaded  with  seven,  and  some- 
times eight  yards.  Six  of  these  cars  supply  this  plant  at  an  average 
output  of  2,500  tons  in  ten  hours.  It  would  take  at  least  three  loco- 
motives and  from  thirty-five  to  forty  6-yard  cars  to  do  the  same  work 
we  are  now  getting  done  with  a  centrally  controlled  electric  haulage 
system.  The  work  of  haulage  of  this  stone  to  and  from  a  quarry,  a 
mile  haul  each  trip,  is  all  accomplished  with  two  operators,  and  there 
is  an  elevation  from  the  crusher  to  the  bottom  of  the  quarry  of  forty 
feet .  .  .  This  equipment  has  50  per  cent,  greater  capacity,  and  the 
cost  of  labor  is  not  25  per  cent,  what  it  would  be  with  locomotives .  .  . 

"I  have  operated'  this  electric  equipment  for  the  last  six  years  or 
more .  .  .  It  is  more  economical  in  every  way;  first  cost,  cost  of  opera- 
tion, cost  of  maintenance,  and  the  convenience  of  having  the  power- 
plant  centrally  located  under  one  roof  is  very  worth  while."  Its  opera- 
tion in  winter,  doing  away  with  boilers  and  water  lines,  is*  favorably 
commented  on. 

"A  steam-shovel  loading  single  cars  has  a  capacity  at  least  15  per 
cent,  greater  than  when  the  cars  are  placed  in  trains  by  locomotives." 
The  reason  given  is  that  the  track  is  kept  clean  of  stones  without 
separating  cars. 

"Another  feature  that  makes  it  more  convenient  is  that  in  the  source 
of  power  there  is  a  greater  number  of  units.  If  one  is  disabled,  the 
chances  are  that  there  is  another  to  take  its  place.  The  plant  is  not 
liable  to  as  much  delay  as  if  it  were  depending  on  two  or  three  loco- 
motives. 

"The  cost  of  operating -the  electrical  equipment  is  only  about  25 


74  STEAM  SHOVEL  MINING 

per  cent,  of  the  cost  of  operating  a  steam-haulage  system.  .  .  It  is 
applicable  for  any  haulage  system  within  a  reasonable  distance,  such 
as  gravel  pits,  clay  pits,  iron  ore,  etc. 

Mr.  W.  R.  Casparis,  of  the  Casparis  Stone  Co.,  states: 

"I  give  the  following  reasons  why  I  personally  favor  electric  haulage 
where  the  conditions  are  permanent,  such  as  a  stone  quarry,  brick 
plant,  etc. 

First:  The  great  saving  of  men  and  labor. 

Second:  The  steep  grades  which  this  class  of  equipment  can  easily 
negotiate.  It  is  not  an  uncommon  thing  for  us  to  operate  a  car  over 
6  to  10  per  cent,  grades. 

Third:  The  rapidity  with  which  the  cars  operate  over  fair,  and  even 
bad  track,  owing  to  the  spring  construction,  and  having  only  four 
wheels,  they  quickly  equalize.  (This  speed  is  from  six  to  twenty  miles 
per  hour). 

Fourth:  The  electric  haulage  affords  the  maximum  movement  of 
material  with  a  minimum  amount  of  equipment.  The  eight  (10-yard) 
cars  we  have  in  operation  are  capable  of  hauling  3000  ton  of  stone  in 
10  hours. 

Fifth:  The  comparative  ease  with  which  electric  haulage  is  operated. 
as  there  are  no  locomotives  to  coal,  water  and  watch  at  night." 

Considerable  space  has  been  given  to  the  foregoing  system  as 
it  is  one  of  much  merit  where  conditions  permit  its  use.  It 
would  not  be  adaptable  for  very  slow  loading,  or  where  heavy 
fog  or  dense  smoke  was  liable  to  cut  off  the  towerman's  view 
from  the  important  points  along  the  track.  If  the  distance  from 
the  loading  points  to  the  crusher  or  dumping  point  was  very 
considerable  it  would  lose  its  advantages.  .There  would  be 
more  costly  equipment  tied  up  in  long  distance  travel  and  a 
higher  percentage  of  tare  weight,  than  if  long  trains  of  large 
capacity  cars  were  hauled  with  heavy  locomotives.  At  many 
open-pit  mines  the  ore  is  loaded  directly  into  ore  cars  which  are 
hauled  out  of  the  pit  and  switched  into  an  assembly  yard  where 
they  are  made  up  into  heavy  trains  for  transportation  many 
miles  to  discharging  points.  In  this  case  there  is  no  transfer 
of  the  ore  and  the  system  would  not  be  adaptable,  but  if  a  crusher 
was  located  within  a  mile  or  two  of  the  loading  points,  or  if  the 
material  was  to  be  placed  on  stock  piles  or  waste  dumps,  the 
system  might  be  profitable  to  adopt,  and  should  be  considered. 

Following  is  a  list  of  installations  of  Woodf  ord  haulage  systems 
serving  power-shovels  in  stone  quarries,  with  daily  capacities, 
etc;— 


MECHANICAL  EQUIPMENT  75 

Dolese  &  Shepard  Co.,  Chicago  111.,  4000  tons,  average  haul  one  mile, 
three  shovels.  Installed  in  1909. 

Missouri  Iron  Company,  Waukon,  Iowa.  1500  tons,  average  haul  one 
half  mile,  one  shovel.  Installed  in  1910.  Plant  not  in  operation. 

Laurin  &  Leitch  Eng.  &  Constr.  Co.,  Beaver  Hall  Sw.,  Montreal,  Canada. 
3000  tons,  average  haul  one  half  mile,  two  shovels.  Installed  in  1911. 

Casparis  Stone  Company,  Kenneth,  Ind.  3000  tons,  average  haul  one 
half  mile,  two  shovels.  Installed  in  1914. 

Temescal  Rock  Company,  Corona,  Cal.  1000  tons,  average  haul  one 
half  mile,  one  shovel.  Installed  in  1915. 

Michigan  Alkali  Company,  Alpena,  Michigan.  6000  tons,  average  haul 
one  mile,  five  shovels.  Installed  in  1916. 

Virginian  Limestone  Corporation,  Ripplemead,  Va.  2000  tons,  average 
haul  one  half  mile,  one  shovel.  Installed  1916. 

Laurin  &  Leitch  Eng.  &  Constr.  Co.,  Montreal,  Canada.  3000  tons 
average  haul  one  half  mile,  two  shovels.  Installed  1918. 

Bessemer  Limestone  Co.,  Youngstown,  Ohio.  1000  tons,  average  haul 
one  half  mile,  one  shovel.  Installed  in  1919. 

Oklahoma  Portland  Cement  Co.,  Ada,  Okla.  2000  tons,  average  haul 
one  half  mile,  two  shovels.  Installed  in  1919. 

The  Woodford  Company  is  now  building  a  system  for  the  Marble  Cliff 
Quarries  Company  of  Columbus,  Ohio,  which  is  expected  to  serve  four 
shovels  on  a  two  mile  haul. 

CARS     i 

Stripping  Cars. — The  cars  employed  for  the  removal  of  over- 
burden are  of  numerous  types  and  designs,  but  they  may  all  be 
classed  either  as  of  the  platform,  the  gondola  or  the  dumping 
type. 

Platform  Type. — The  platform  cars  are  the  simplest,  consisting 
of  a  heavy  platform  of  wood,  sometimes  armored,  supported  on 
two  four-wheel  standard  trucks.  The  sides  of  the  platform  are 
provided  with  stake-pockets  to  receive  short  vertical  posts 
which  guide  the  unloading  device,  and  at  one  end  of  each  car  is 
a  hinged  sheet-steel  apron  as  wide  as  the  platform  and  long 
enough  to  bridge  over  the  coupler  space  to  the  next  car,  forming, 
as  it  were,  a  continuous  support  or  bed  for  the  unloader.  These 
cars  are  about  34  ft.  long  and  7  ft.  wide,  and  carry  about  10  cu. 
yds.  of  earth  or  broken  rock.  The  brake  wheels  must  be  placed 
at  the  side  of  the  car. 

When  arranged  in  this  way  they  can  be  unloaded  by  a  plow- 
like  contrivance  which  rests  on  the  platform  of  the  rear  car. 
A  steel  cable  is  attached  to  the  plow  and  to  the  locomotive,  and, 
when  the  dumping  place  is  reached,  the  aprons  are  lowered  and 
the  locomotive  is  detached  and  slowly  moved  ahead,  drawing 


76  STEAM  SHOVEL  MINING 

the  plow  along  the  length  of  the  train  and  cleaning  the  car 
platforms  of  material.  To  avoid  detaching  and  moving  the 
locomotive  ahead,  the  Lidgerwood  Manufacturing  Company 
has  designed  a  plow  with  the  cable  attached  to  a  single-drum 
reversible  engine  located  at  the  front  end  of  the  first  car  close 
to  the  locomotive  and  deriving  steam  for  operation  from  the 
locomotive.  This  does  the  unloading  in  the  same  way.  The 
material  may  be  unloaded  either  to  the  right  or  the  left  or  on 
both  sides  simultaneously  depending  on  the  set  and  shape  of 
the  plow.  The  engine  is  capable  of  exerting  a  pull  on  the  cable 
of  about  25  tons  and  winding  at  a  speed  of  125  ft.  per  minute, 
thus  unloading  the  train  quickly  and  cheaply. 

Gondola  Type. — The  ordinary  gondola  car  is  of  similar  con- 
struction to  the  platform  car  but  has  permanent  sides  and  ends 
about  3  ft.  high.  They  hold  from  25  to  40  cu.  yds.  and  are  con- 
venient for  hauling  some  classes  of  material  long  distances. 
They  must  be  unloaded  by  hand,  (or  with  some  type  of  derrick 
excavator)  and  as  this  is  slow  and  expensive  they  are  seldom 
used  for  overburden  removal,  but  often  for  coaling  shovels  and 
locomotives.  For  coaling  purposes  specially  constructed  cars 
of  this  type  are  sometimes  advantageously  used. 

Dumping  Type — Air  or  Hand  Operated. — By  far  the  greatest 
number  of  cars  in  stripping  service  are  of  the  dumping  type, 
of  which  there  is  a  large  variety  on  the  market. 

For  the  purpose  of  removing  overburden  side-dump  cars  are 
made  in  capacities  of  from  1J^  cu.  yds.  to  30  cu.  yds.  level-full 
or  " water  measure".  They  are  built  to  dump  on  one  side  or 
both,  the  smaller  sizes  being  dumped  by  hand,  and  the  larger 
sizes,  say,  from  12  cu.  yds.  up,  either  by  hand  or  by  air.  The 
smaller  sizes,  say,  up  to  10  cu.  yds.,  are  equipped  with  two  two- 
wheel  trucks  and  are  of  wood  construction;  the  larger  sizes  have 
two  four-wheel  trucks  and  are  built,  on  M.  C.  B.  specifications, 
of  wood,  wood  and  steel  or  all  steel.  There  are  also  used  for 
some  purposes  bottom-dump  and  end-dump  cars  built  in  vari- 
ous sizes,  designs  and  materials. 

In  present  practice  on  large  works,  side-dump  cars  carrying 
from  12  to  30  cu.  yds.  of  all  steel  construction  are  proving  most 
satisfactory.  Some  cars  of  this  type  have  a  line  of  pivot  pin- 
bearing  dumping-centres  and  others  dump  on  rockers  located 
on  either  end  of  the  car  over  the  bolster.  The  latter  method 
gives  easier  action  with  less  shock  to  the  car  but  does  not  com- 


MECHANICAL  EQUIPMENT  77 

pact  the  material  dumped  so  well,  nor  keep  the  far  side  of  the 
bottom  so  clean  as  when  it  is  dumped  more  violently.  Con- 
solidating the  dumped  overburden  is  an  advantage  in  dump 
building  when  the  dump-track  is  later  to  be  extended  thereon, 
and  keeping  the  car  clean  is  essential,  so  that  if  the  pin-bearing 
car  is  well  designed  with  ample  provision  made  for  the  shock 
and  impact  of  dumping,  there  is  no  serious  mechanical  objection 
to  this  type. 

Another  varying  feature  is  the  movement  of  the  side  doors, 
some  having  rising  doors  and  some  having  folding  or  drop-doors. 
The  drop-door  virtually  forms  a  stepped -down  extension  to  the 
car  floor  and  greatly  assists  in  discharging  the  material  farther 
from  the  car  and  track.  If  the  rising-door  type  is  provided  with 
extended  bottom-plates,  on  which  the  doors  may  rest,  this 
outward  disposal  is  similarly  accomplished.  If  the  loading  and 
dumping  can  be  so  arranged  that  the  cars  are  required  to  dump 
from  one  side  only,  they  have  decided  mechanical  advantages 
in  construction  and  are  considered  safer  in  mining,  as,  on  being 
righted  after  dumping,  they  cannot  come  all  the  way  over  and 
hit  the  men. 

It  is  still  a  debated  point  as  to  whether  air-dumped  or  hand- 
dumped  cars  are  most  efficient  and  economical,  and  the  answer 
will  generally  depend  on  the  local  conditions  of  the  particular 
problem  for  which  the  cars  are  intended.  Hand-dumped  cars 
up  to  20  cu.  yds.  capacity,  level-full,  may  be  dumped  without 
difficulty,  but  for  larger  sizes,  the  car  is  likely  to  be  so  heavy 
that  hand-dumping  ,or  rather  righting,  may  be  awkward. 

The  air-dumping  device  is  operated  by  compressed  air  from 
the  locomotive.  This  is  derived  from  the  air-brake  pump  and  is 
conveyed  to  the  car  reservoirs  and  dumping  cylinders  by  special 
independent  train  lines  similar  to  the  air-brake  lines.  Some 
types  of  air-dumped  cars  are  operated  by  a  single  lever  for  each 
side  which  controls  the  unlocking,  dumping,  righting  and  re- 
locking  of  each  car.  Each  lever  governs  the  action  of  an  air- 
piston  situated  at  its  respective  side  of  the  car  and  between  the 
trucks.  In  operation,  the  piston  at  one  side  pushes  the  car-body 
over,  the  piston  at  the  opposite  side  pushes  it  back.  By  means 
of  a  system  of  valves  through  which  the  air  is  admitted  to  the 
dumping  cylinder  the  air  is  automatically  shut  off  when  the 
right  amount  for  dumping  the  car  has  passed,  avoiding  air 
wastage.  The  air  is  thus  applied  directly  to  the  car  and  no 


78  STEAM  SHOVEL  MINING 

power  is  wasted.  The  doors  are  automatically  raised  in  dumping 
and  are  held  in  the  proper  position  for  free  clearance  of  the  dump- 
ing load.  The  doors  may  be  so  hung  or  pivoted  that  they  are 
free  to  swing  out  when  struck  by  rocks,  making  for  less  liability 
of  choking  or  of  overturning  the  car.  All  steel,  16  or  20-cu.  yd. 
cars  of  this  type  are  in  general  use  in  the  Mesabi  iron  mines. 
They  are  built  by  the  Western  Wheeled  Scraper  Co.,  and  the 
Kilbourne  &  Jacobs  Company,  those  of  the  latter  having  the 
following  general  dimensions: — 

Type R-20  C-16 

Angle  of  dump 45°  45° 

Gauge 4  ft.  8K  in. '  4  ft.  8^  in. 

Height— top  of  rail  to  top  of  body 8  ft.  5^  in.  7  ft.  10>i  in. 

Height — top  of  rail  to  center  of  draw  bar .  34^  in.  34^  in. 

Length  over  couplers 32  ft.  OK  in.  30  ft.  03^  in. 

Length  over  end  sills 29  ft.  5^  in.  27  ft.  6>£  in. 

Body  depth 2  ft,  4  in.  2  ft.  0  in. 

Length  inside 26  ft.  0  in.  24  ft.  0  in. 

Inside  width 8  ft.  10  in.  9  ft.  0  in.. 

Maximum  width 10  ft.  6  in.  10  ft.  6  in. 

Truck  centres 16  ft.  0  in.  16  ft.  0  in. 

Truck  wheel  base 5  ft.  6  in.  5  ft.  4  in. 

Approx.  weight,  Ibs 48,000  42,500 

Another  dump-car,  known  as  the  Goodwin,  is  constructed 
of  steel  and  divided  into  two  compartments  which  can  be  un- 
loaded separately  because  of  the  dividing  steel  diaphragm. 
The  discharging  mechanism  can  be  operated  either  by  air,  steam, 
electricity  or  hand-power.  It  can  be  discharged  on  either  or 
both  sides,  or  in  the  center,  according  to  the  different  manner  of 
manipulating  the  bottom-plates  and  side-doors.  Discharging 
can  be  done  with  safety  while  running  at  any  speed,  and  in  this 
way  the  material  can  be  spread  for  a  considerable  distance 
from  the  track.  Dumping  all  or  any  number  of  the  cars  is 
done  by  one  man  in  any  part  of  the  train.  For  stripping  service, 
however,  these  cars  are  seldom  used  as  they  are  not  sufficiently 
rugged  and  simple. 

A  hand-dumped  car  of  20  cu.  yd.  capacity  and  dumping  from 
one  side  only,  which  has  been  found  to  give  very  satisfactory 
service,  is  illustrated  in  Figs.  15  and  16.  Desirable  features  will 
be  noted  in  the  all-steel  construction,  extended  bottom,  one-way 
dump,  wood  buffer-sills,  steep  dumping  angle,  pivoted  door  and 
self-righting  balance.  The  one-way  dump  adds  to  its  mechanical 


MECHANICAL  EQUIPMENT 


79 


strength  and  the  steep  47°  angle  assists  in  discharging  sticky  or 
partly  frozen  material.     Such  cars  cost  about  $2500  each.     Where 


it  is  necessary  to  maintain  dump-gangs,  as  is  usually  the  case, 
these  cars  can  be  dumped  by  that  labor  about  as  quickly  as  the 


80 


STEAM  SHOVEL  MINING 


MECHANICAL  EQUIPMENT  81 

air-dumped  type;  furthermore  it  is  often  necessary  to  "respot" 
the  train  to  dump  the  material  where  desired  and  in  such  cases 
there  is  no  advantage  in  being  able  to  dump  all  cars  simul- 
taneously. Under  such  usual  conditions  it  will  be  found  that 
this  car,  being  of  simpler  construction,  will  stay  in  service  longer, 
require  fewer  repairs  and  be  more  economical  to  operate  than 
those  dumping  by  air.  The  company  using  this  car  has  made 
many  changes  in  the  size  of  dump  cars  since  operations  were 
started.  The  first  cars  used  were  6-cu.  yd.  two-way  dump-cars, 
next  came  12-cu.  yd.  cars  with  one-way  dump,  these  were  dis- 
carded for  18-cu.  yd.  cars  and  now  the  20-cu.  yd.  car  is  standard. 
The  factors  governing  the  size  of  the  cars  are  the  height  of  centre 
of  gravity,  the  amount  of  dead  weight  per  cubic  yard  capacity  and 
the  number  of  cubic  yards  which  can  be  hauled  per  trip.  Among 
the  builders  of  both  types  may  be  mentioned  the  Kilbourne  & 
Jacobs  Manufacturing  Co.,  Columbus,  Ohio;  Oliver  Manufac- 
turing Co.;  Western  Wheeled  Scraper  Co.,  Aurora,  111.;  Continen- 
tal Car  and  Equipment  Co.,  Highland  Park,  Ky.;  Clark  Car  Co., 
Pittsburg,  Pa., 

Ore  Cars.- — Hopper  Bottom  and  Gondola  Types. — For  loading 
and  transporting  ores  short  distances  dump-cars  may  be  used, 
but  if  the  distance  be  considerable  a  different  type  of  car  should 
be  adopted.  For  hauling  iron  and  copper  ores  heavy  all-steel  cars, 
constructed  on  standard  M.C.B.  specifications  and  carrying  from 
50  to  70  tons  are  the  usual  sort.  These  are  designed  with  a 
variety  of  automatic  or  hand-'dumping  bottoms  or  valves.  They 
are  usually  required  to  dump  over  a  bin,  trestle  or  dock.  The 
Ingoldsby  type  is  of  this  variety  and  is  a  very  satisfactory  car. 
Such  cars  are  built  by  the  Pullman  Company  and  other  standard 
car  builders.  They  cost  about  $2800  each  for  those  of  60  tons 
capacity.  Having  been  loaded  directly  by  the  shovels,  they  are 
usually  hauled  from  the  pit  to  an  assembly  yard  by  the  regular 
pit  locomotives,  and  there  made  up  into  standard  trains  for 
distant  transport  by  heavy  freight  locomotives  of  the  consoli- 
dation or  Mallet  type.  To  stand  the  strain  of  shovel  loading  and 
hard  heavy  service  these  cars  must  be  of  very  strong  construc- 
tion. For  this  reason  some  companies  have  preferred  to  use  for 
ore  service  heavy  steel  cars  of  the  gondola  type  eliminating  all 
dumping  mechanism.  For  this  type  it  is  usual  to  provide  a 
revolving  or  mechanical  tipple  of  some  sort,  the  use  of  which 
requires  the  uncoupling  and  recoupling  of  the  train  and  is  there- 


82  STEAM  SHOVEL  MINING 

fore  slower.  Also  the  tipple  must  be  operated  and  kept  in  re- 
pair, so  that  while  the  upkeep  and  first  cost  of  the  ore  cars  is 
less,  this  advantage  may  be  largely  offset  by  the  slower  dumping 
and  the  upkeep  and  first  cost  of  the  tipple.  A  study  of  the  con- 
ditions under  which  the  ore  trains  are  to  operate  will  usually 
indicate  the  better  type  to  adopt. 

TRACK 

General  Pit-Track. — As  a  rule  in  pit  approaches  and  assembly 
yards,  and  even  track  on  some  of  the  benches,  may  be  considered 
sufficiently  permanent  in  character  to  warrant  the  spending  of 
sufficient  money  to  put  it  in  first  class  condition.  Such  work 
should  if  possible,  be  laid  out  with  not  over  2  per-cent.  compen- 
sated grade,  and  yet  not  necessitate  unduly  steep  pit-tracks. 
On  large  work  such  track  should  be  laid  with  4ft.  8J^  in.  gauge 
and  75  or  80  Ib.  rail.  Care  should  be  taken  to  keep  good  grade 
and  alignment  and  provide  proper  ballast.  The  curves  should 
be  made  as  easy  as  posible;  as  a  rule  10°  is  considered  the  sharp- 
est desirable  and  20°  the  maximum  allowable.  In  the  pit  itself 
50°  curves  are  sometimes  unavoidable  and  can  be  operated  over 
without  a  great  deal  of  trouble  when  carefully  laid  and  main- 
tained. For  the  more  or  less  permanent  track  2%  per  cent, 
grade  should  be  the  maximum  although  3  per  cent,  is  sometimes 
necessary.  The  pit  grades  are  likewise  kept  down  as  low  as 
practicable,  but  at  times  5  per  cent,  and  even  up  to  7  per  cent, 
has  been  found  unavoidable  for  very  short  runs.  The  great 
increase  in  motive  power  required  upon  heavy  grades  has  been 
emphasized,  and,  while  it  is  very  desirable  to  keep  within  the 
approved  limits  of  grade  and  curvature,  nearly  every  mine  has 
at  times  found  it  possible  and  necessary  to  exceed  what  may  be 
considered  practical  railroad  conditions. 

In  planning  pit-trackage,  the  elipse  or  spiral  is  to  be  preferred 
to  switch-backs,  since  lighter  grades  and  easier  curves  and  turn- 
outs are  secured;  but  to  employ  this  system  the  pit  must  be  large 
and  roughly  uniform  in  plan.  Long,  narrow  or  irregular  pits 
or  faces  of  ore  must  usually  be  worked  with  switchbacks. 

It  is  just  as  essential  to  have  competent  and  experienced  track 
foremen  for  this  class  of  work  as  for  main-line  railroad  work. 

Definitions  and  Rules.1     Track. — " Track"   consists  of  ties, 

1  Definitions  and  recommendations  according  to  American  Railway  Engi- 
neers Association. 


MECHANICAL  EQUIPMENT  83 

rails  and  fastenings;  with  all  parts  in  their  proper  relative  po- 
sitions. 

Track  is  a  subject  given  the  closest  attention  in  good  railroad 
practice  but  often  neglected  in  mining  operations.  It  is  imprac- 
ticable to  give  shovel-mine  tracks  the  same  great  care  and  atten- 
tion that  are  demanded  for  main-line  railroad  work  because  of 
their  temporary  character,  but  nevertheless  it  will  be  found 
highly  economical  to  equip  and  maintain  pit  and  yard  tracks  in  as 
good  shape  as  the  conditions  warrant.  Poor  track  causes  many 
expensive  wrecks  and  derailments,  produces  much  wear  and  tear 
on  the  rolling  equipment  and  may  very  seriously  cut  down  the 
efficiency  of  the  motive-power. 

The  problems  of  grades  and  curvatures  were  previously  dis- 
cussed with  their  effects  on  the  hauling  capacity  of  locomotives. 
The  resistance  due  to  rolling  friction  was  shown  to  vary  over 
wide  limits,  say,  from  6  to  30  pounds  per  ton,  and  to  be  dependent 
on  the  condition  of  the  rolling-stock  and  the  track. 

Alignment. — By  " alignment"  is  meant  the  horizontal  location 
of  a  railway  with  reference  to  curves  and  tangents.  It  is  desir- 
able to  keep  the  alignment  uniform  in  direction  over  tangents 
(straight  track)  and  of  uniform  variation  over  curves.  For 
permanent  work  " witnesses"  should  be  placed  at  points  of  tan- 
gent, points  of  spiral,  points  of  change  of  curvature,  summits 
and  such  other  points  along  the  line  as  -will  enable  the  alignment 
to  be  identically  reproduced  with  a  transit.  For  temporary 
track  such  refinements  are  impractical  but  by  proper  use  of  such 
auxiliary  fastenings  as  nutlocks,  tie  plates,  rail  braces  and  various 
anti-creeping  devices  track  can  be  maintained  in  fair  alignment. 

Curves. — A  " curve"  is  a  change  in  direction  by  means  of  one 
or  more  radii.  The  curve  is  simple  when  the  change  in  direction 
is  made  by  means  of  a  single  radius.  The  curve  is  compound 
when  the  change  consists  of  two  or  more  simple  curves  of  different 
radii,  but  in  the  same  general  direction,  joining  one  another  at 
points  having  a  common  tangent.  The  curve  is  reverse  when 
two  curves  have  opposite  general  directions,  but  joining  one 
another  at  a  common  tangent  point.  The  curve  is  vertical  when 
used  to  connect  intersecting  grade  lines.  The  degree  of  curve 
is  the  central  angle  subtended  by  a  100-foot  chord.  Easement 
of  curve  is  effected  when  a  curve  having  a  radius  of  regularly  vary- 
ing length  connects  a  tangent  to  a  simple  curve,  or  connects  two 
simple  curves.  Such  a  curve  is  also  spoken  of  as  a  transition 


84  STEAM  SHOVEL  MINING 

curve.  "Elevation",  as  applied  to  curves,  is  the  amount  by 
which  the  outer  rail  is  raised  above  the  inner  rail. 

To  determine  the  degree  of  a  curve  closely  enough  for  practical 
purposes,  take  the  middle  ordinate  of  a  62-foot  chord  laid  off  on 
the  inside  rail;  the  length  of  this  middle  ordinate  in  inches  ap- 
proximately equals  the  degree  of  curvature. 

The  amount  by  which  the  outer  rail  should  be  elevated  on  a 
curve  may  be  determined  from  the  following  formula: 

E  =  0.00066DV2 

Where  E  =  elevation  of  outer  rail  in  inches. 
D  =  degree  of  curve 
V  =  velocity  of  train  in  miles  per  hour. 

An  elevation  of  eight  inches  should  not  be  exceeded. 

Gauge. — The  " gauge"  of  track  is  the  distance  inside  between 
the  heads  of  the  rails,  measured  at  right  angles  thereto  and  at  a 
point  5^  inch  below  the  top  of  the  rail.  Gauge  is  said  to  be 
" standard"  when  this  distance  is  4  ft.  8J^  in. 

The  spread  of  rails  on  curves  of  8°  or  under  should  remain 
standard,  but  for  each  2°  or  fraction  thereof  over  8°,  the  gauge 
should  be  widened  %  in  up  to  a  maximum  of  4  ft.  9J£  in.  Gauge, 
including  widening  due  to  wear,  should  never  exceed  4  ft.  9J^  in. 

The  installation  of  frogs  upon  the  inside  of  curves  is  to  be 
avoided  where  practicable,  but  when  unavoidable,  the  above  rule 
should  be  modified  to  make  the  gauge  of  the  track  at  the  frog 
•standard. 

The  sharpest  curve  to  which  two  fixed  pairs  of  flanged  wheels 
will  adjust  themselves,  depends  upon  their  distance  apart,  the 
diameter  of  the  wheels  and  the  size  and  shape  of  the  flanges. 
Assuming  the  M.C.B.  standard  for  flanges  and  rails  and  that  the 
gauge  is  not  widened  on  the  curve,  a  sufficiently  accurate  formula 
for  all  practical  purposes  is  as  follows: 

P          W 

K    =   ~ : 

2  sin  a 

Where  R  =  radius   in  feet   of   sharpest   curve   that   can   be 

passed, 

W  =  wheel-base  in  inches 
a  —  angle  the  flanged  wheels  make  with  the  rails. 

The  value  of  sin  a,  for  various  diameters  of  wheel,  is  given 
below : 


MECHANICAL  EQUIPMENT  85 


Diameter  of  wheels  (inches)    .  .  . 
Value  of  sin  a  

20-24 
0.117 

25-30 
0.107 

31-40 
0.099 

41-50 
0.08 

51-60 
0.075 

If  intermediate  wheels  are  introduced  between  the  two  pairs  of 
flanged  wheels,  their  relation  with  the  rail  requires  a  separate 
consideration. 

When  a  truck  is  used  the  swing  must  be  sufficient  to  allow 
the  locomotive  to  pass  the  curve. 

Adjustment  of  curves  and  refinement  in  laying  them  out, 
should  be  done  by  a  competent  trackman  or  engineer.  The 
theory  of  curves  will  be  found  in  such  handbooks  as  Searles, 
Crandall,  Holbrook  and  Talbot. 

Maintenance. — " Maintenance"  means  preserving  the  track 
on  proper  grade,  in  alignment  and  in  repair.  The  surface  is 
maintained  with  some  kind  of  ballast,  such  as  earth  or  clay, 
cinders,  burnt  clay,  broken  stone  or  gravel,  and  the  ties  are  tamped. 
The  tools  required  for  tamping  are  shovels,  tamping-bars  and 
picks.  The  method  suggested  for  ordinary  work  is  to  tamp  each 
tie  from  18  inches  inside  of  the  rail  to  end  of  tie  with  shovel- 
handle  or  tamping-bar.  It  is  best  to  tamp  the  end  of  the  tie 
outside  of  the  rail  first  and  then  let  a  train  pass  over  before 
tamping  inside  of  the  rail.  Give  particular  attention  to  tamping 
under  the  rail  and  tamp  the  center  loosely  with  the  blade  of  the 
shovel.  The  dirt  between  the  ties  should  be  placed  in  layers 
and  firmly  packed  with  the  feet  or  otherwise,  so  that  it  will 
quickly  shed  the  water;  the  earth  should  not  be  banked  above 
the  bottom  of  the  ends  of  the  ties;  and  the  ballast  filling  between 
the  ties  should  not  tou'ch  the  rail,  but  in  the  track  centre  should 
be  as  high  as,  or  higher  than,  the  top  of  the  ties. 

When  not  surfacing  out  of  face,  as  when  picking  up  low  joints 
or  other  low  places,  the  general  level  of  the  track  should  not  be 
disturbed.  Where  the  rails  are  only  slightly  and  not  abruptly 
out  of  level,  the  track  may  be  safely  operated  over  until  such 
time  as  it  would  ordinarily  be  surfaced  out  of  face. 

To  maintain  the  gauge,  or  prevent  spreading  of  the  track  and 
canting  of  rails  on  curves,  various  devices  are  resorted  to.  Tie- 
plates  are  recommended  in  all  cases  for  the  preservation  of  ties, 
and  in  general  better  maintenance  will  result  from  their  use. 
Shoulder  tie-plates  are  recommended  in  preference  to  rail-braces, 
except  for  guard-rails  and  stock-rails  at  switches,  where  the 
latter  should  be  used.  For  heavy  or  even  medium  traffic, 


86          STEAM  SHOVEL  MINING 

shoulder  tie-plates  should  be  used  on  all  ties  on  curves  of  over 
three  degrees.  For  light  traffic  on  easy  curves  the  outside 
of  rails  on  such  curves  should  be  double  spiked. 

In  gauging  track  the  standard  gauge  tool  should  be  used; 
slight  variation  of  gauge  from  the  standard,  say  up  to  one-half 
inch,  is  not  seriously  objectionable  if  the  variation  is  not  abrupt. 
Wide  gauge,  due  to  worn  rail  and  up  to,  say,  one-half  inch,  is  not 
objectionable,  but  when  excessive  should  be  corrected  by  closing  in. 

Where  track  is  to  be  spiked  to  standard  gauge,  the  rail  should 
be  held  against  the  gage  with-  a  bar  while  the  spike  is  being 
driven.  The  spikes  should  be  started  vertically  and  square,  and 
so  driven  that  the  face  of  the  spike  comes  in  contact  with  the 
base  of  the  rail;  the  spike  should  never  have  to  be  straightened 
while  being  driven.  The  outside  spikes  of  both  rails  should  be  on 
the  same  side  of  the  tie,  and  the  inside  spikes  on  the  other.  The 
inside  and  outside  spikes  should  be  spaced  as  far  apart  as  the 
face  and  character  of  the  tie  will  permit.  The  ordinary  practice 
is  to  drive  the  spike  2J^  inches  from  the  edge  of  the  tie;  old 
spike  holes  should  be  plugged. 

With  standard  gauge  track  the  width  of  standard  flangeways 
for  all  frogs  and  between  main-rails  and  guard-rails  should  be 
1%  inches,  measured  at  the  gauge  line. 

The  widening  of  gauge  on  curves  has  been  mentioned. 

The  allowance  that  should  be  made  for  expansion  for  33-foot 
rails  is  as  follows  (the  temperature  is  to  be  taken  on  the  rail,  and 
the  openings  given  are  between  the  rail  ends.) 


Temperature-degrees,  Fah... 
Allowance-inches  

-20  to  0 
H« 

0  to  +25 

H 

25  to  50 

Mo 

50  to  75 

M 

75  to  100 
KG 

At  over  100°F.  rails  should  be  laid  close  but  without  bumping. 
The  expansion  should  always  be  uniform  and  by  observing 
this  and  using  care  in  placing  plates  and  in  spiking  much  can 
be  done  to  prevent  creeping  track. 

In  the  pits  and  on  the  dumps  there  is  almost  constant  track 
shifting  to  be  done.  This  is  still  largely  done  by  hand,  but  track 
shifting  machines  have  been  devised  which  speed  up  and  cheapen 
this  operation.  One  satisfactory  type  of  shifter  used  on  the 
Mesabi  range  resembles  a  wrecker  in  general  appearance  and 
has  two  booms  about  40  feet  long,  one  for  lifting  the  track 
and  the  other,  on  a  level  with  the  base  of  the  machine,  for  side- 


MECHANICAL  EQUIPMENT 


87 


pulling  it.  The  machine 
is  self-propelling,  has  one 
hoist  of  simple  type  and 
one  horizontal  boiler.  The 
machine  has  a  side-throw 
of  6  feet,  but  the  usual 
method  employed  is  to 
shift  over  about  4  feet 
and  then  move  the  shifter 
back  30  feet  and  repeat  the 
operation.  In  doing  the 
work  thus  gradually  serious 
bending  or  twisting  of  the 
rails  is  avoided.  It  is 
claimed  that  as  much  as 
3000  feet  of  track  has  been 
shifted  10  feet  in  half  a 
day  whereas  to  do  this  by 
hand  40  or  50  men  would 
have  been  required  for  a 
full  day.  These  machines 
are  desirable  labor  savers 
when  much  track  shifting, 
as  on  dumps,  is  to  be  done. 

Materials  and  Equip- 
ment.— In  the  following 
table  are  given  the  re- 
quirements for  one  mile 
of  track. 

When  using  railroad 
type  of  shovels,  each  shovel 
will  be  equipped  with 
about  6  ft.  track  sections, 
36  ties,  2  or  3  pairs  of  good 
rail  clamps,  2  large  and  2 
small  jack  blocks. 

Rail. — The  sustaining 
power  of  the  same  weight 
of  rail  varies  greatly  with 
different  tie-spacings,  road- 
beds, etc.,  but  it  has  been 


3.S.S 


f+S 


saqoui 
saa^uao  atx 


CO   CO   CO   <N    <N 


00   <N    T^    CO   CO    00   O 


00   O   O   <N   00   TJ*   CO 

CO    00    "*    -*    CO    GO    *O 

r-^  00^   CO^  -^   <N^   r-^   01 


^  CO  00  <N 
i—  1  lO  d  >O 
OO  1^*  1s**  CO 


00   O   O   t~   00 
<N    00   rt<   O   t-- 

Ut)    Tt<    T*<    rt<    CO 


O    (N    TH    CO   00   O    CO 
<N    <M    (N    (M    (M    CO   CO 


^H    T^    cO    O^    CO 
iO   lO   »O   1C   CO 


O   O   O   <M    00   O   O 
"^    CO    00    ^^    ^D    ^^    C^l 

»o"  co"  t>-"  oo"  oT  o"  T-T 

I—I      TH      T-H      T-t      T-H      (N      (N 


t-i    CO   "^    CO    00   O 
CO    CO    CO    CO    CO    ^ 


»O   O   lO   O   cO^  CO 

o"  i-T  T-T  <M"  <N"  co" 


o  o  ^  co  o  o 

iO   ^O   CO    CO   CO   !>• 


f~>   \f$    ^^   !>•   GO   *O    CO 
rt<    iO   00   T-H    cO    CO    <N 

CO   !>•    GO   O_  T-H^  CO_  iO_ 

<N"  <N"  <N"  co"  co"  co"  co" 


CO   <N   I-H   O   O5   00 
(N    O5    <M    (M    rH    T-H 


88 


STEAM  SHOVEL  MINING 


found  that   1  Ib.  of  rail  per  yard  will  sustain  from  225  Ib.  of 
driving-wheel  for  the  lighter  rails  to  300  Ib.  for  the  heavier. 

While  any  figures  regarding  carrying  power  of  rails  must  be 
approximate,  those  given  in  the  following  table  represent  the 
limit  of  good  practice,  and  should  not  be  exceeded. 


TABLE  12 


Weight  of 
rail  per  yd., 
ib. 

Greatest  weight 
per  axle, 
Ib. 

Weight  of 
rail  per  yd., 
Ib. 

Greatest  weight 
per  axle, 
Ib. 

Weight  of 
rail  per  yd., 
Ib. 

Greatest  weight 
per  axle, 
ib. 

12 

4,000 

45 

25,000 

75 

48,000 

16 

6,400 

50 

28,000 

80 

52,000 

20 

9,000 

55 

33,000 

.    85 

57,000 

25 

11,400 

60 

38,000 

90 

62,000 

30 

15,000 

65 

40,000 

95 

66,000 

35 

18,000 

70 

44,000 

100 

72,000 

40 

22,000 

Notes:  If  the  weight  on  each  axle  is  not  the  same,  the  heavy  weight 
should  be  taken. 

Rails  weighing  80  Ib.  per  yard  are  in  general  use  for  open-pit  trackage 
in  many  places. 

For  the  inspection  and  identification  of  rails  all  rolling  mills 
brand  and  stamp  their  product.  The  raised  brand  gives  the  name 
of  the  manufacturer,  a  number  or  abbreviation  by  which  the 
rail  section  is  designated,  the  month  and  year  of  manufacture, 
and,  if  the  metal  is  open  hearth  steel,  the  letters  "O.H. "  are  added. 

The  rails  while  red-hot,  but  after  having  been  completely 
rolled  and  sawed  to  length,  are  stamped  on  the  web  with  the 
number  representing  the  heat,  blow  or  melt  of  steel,  and  the 
letter  to  indicate  the  position  of  the  rail  in  the  ingot. 

There  are  many  rail  sections,  but  those  in  most  common  use 
are  classed  as  A.S.C.E.  sections  and  A.R.A.  sections,  the  initials 
meaning  American  Society  Civil  Engineers  and  American 
Railway  Association.  The  section  desired  should  be  specified. 
Old  and  worn  rail  is  frequently  used  for  dumps  and  little-used 
track. 

In  purchasing  re-rolled  rails  great  care  should  be  used  as  they 
often  prove  very  defective,  unreliable  and  dangerous.  Some 
unscrupulous  dealers  have  attempted  to  sell  them  as  rail  made 
from  new  steel  billets. 


MECHANICAL  EQUIPMENT  89 

Fastenings  and  Accessories 

Spikes. — Cut-spikes  are  commonly  used  in  the  United  States 
but  in  other  countries  screw-spikes  are  common.  The  latter  are 
being  more  often  recommended  for  permanent  track  because  they 
help  prevent  the  premature  destruction  of  the  wood  fibres  of  the 
tie  caused  by  driving  the  ordinary  square  cut  spike,  and  because 
they  give  a  greater  holding  power  than  the  driven  spike.  The 
sizes  of  both  kinds  vary  for  different  rail  weights  and  conditions. 
Cut  spikes  range  from  3}^  in.  X  %  in.  for  16-lb.  rail  up  to  5j^  in. 
X  %6.in.  for  60-lb.  to  80-lb.  rail. 

Tie  plugs  may  be  had  of  any  wood  desired. 

Tie  Plates. — There  are  many  varieties  of  tie-plates  from  simple 
flat  punched-plates  to  corrugated  shouldered  flanged-plates. 
The  shouldered  flange  tie-plate  with  corrugated  rail  bearing  sur- 
face and  not  less  than  6  in.  wide  by  %  in.  thick,  is  to  be 
recommended  for  soft-wood  ties.  They  may  be  punched  with 
two,  three  or  four  spike-holes  as  desired  and  are  of  various  widths, 
lengths  and  thicknesses  depending  on  the  rail  section  and  use 
they  are  to  serve.  Such  tie-plates  are  made  for  both  cut  and 
screw-spikes.  The  three-hole  punching  permits  the  use  of  the 
plate  for  either  right  or  left  hand  side,  while  a  three  or  four-hole 
punching  may  be  specified  to  serve  two  rail  sections  of  different 
base  width.  In  ordering  intermediate  tie-plates,  give  the  rail  base, 
size  of  spike,  number  of  holes  wanted  and  width  and  thickness  of 
plate;  for  shoulder  tie-plates  add  description  of  angle-bar  used. 

Tie-plates  may  be  inserted  under  the  rail  after  track  has  been 
laid  but  naturally  at  much  greater  convenience  than  if  assem- 
bled with  the  track.  They  may  also  be  punched  with  special 
holes  in  the  field  by  means  of  a  portable  tie-plate  punch. 

Angle  Bars  and  Fastenings. — : Various  forms  of  angle  bars  have 
been  devised  in  an  effort  to  secure  a  continuous  rail-joint  but  the 
standard  bar  is  used  in  pit  service  work.  The  track  bolts  with 
square  nuts,  used  with  lock  nuts,  are  standard.  Where  it 
is  necessary  to  bond  rails  for  signal  purposes,  No.  8  iron  wire 
or  No.  6  copper  wire  is  generally  used  with  size  %2  m-  tin-plated 
channel-pins.  Where  bonding  is  not  practical  for  signal  pur- 
poses, various  rail-deflection  and  vibration  devices  have  been 
designed  by  the  signal  manufacturers. 

Simple  derailing  devices  are  made  for  attachment  to  any  rail- 
section  it  may  be  desired  to  protect. 


90 


STEAM  SHOVEL  MINING 


Tools. — The  track  tools  consist  of  shovels,  picks,  gauges,  drills, 
track-chisels,  spike-mauls,  double-face  hammers,  napping-ham- 
mer,  tie-plate  swages,  track-punches,  tie-plug  punches,  claw- 
bars,  spike-pullers,  pinch-bars,  lining-bars,  tamping-bars  and 
picks,  rail-tongs  and  track-wrenches.  They  may  be  had  from 
any  railway  supply  company. 

Ties. — Timber  ties  are  used,  both  treated  and  untreated. 
With  increasing  scarcity  and  cost  of  timber  suitable  for  ties, 
treating  is  becoming  more  general;  some  steel  ties  are  also  being 
used,  but  they  have  not  yet  met  with  general  favor  for  this  class 
of  work  for  a  number  of  reasons. 

The  usual  methods  of  treating  ties  are  by  injecting  zinc  chloride 
into  the  fibre,  called  Burnettizing;  injecting  zinc  tannin,  the 
Wellhouse  process;  zinc  creosote,  the  Card  process;  creosoting 
by  the  Lowry  or  Rueping  processes;  and  Wood  creosoting. 

The  estimated  life  of  untreated  and  treated  ties  in  the  United 
States  is  given1  as  follows: 

TABLE  13 


Species 


Estimated  life  (all  ties  properly  tie-plated) 


Untreated 
years 


Treated  with 

10  Ibs.  creosote 

per  cu.  ft. 

years 


Treated  with 
0.5  Ibs.  zinc 
chloride  per 

cu.  ft., 

years 


Black  locust. 20 

Redwood 12 

Cedar 11 

Cypress 10 

White  oaks ". 8 

Longleaf  pine 7 

Chestnut „ 7 

Douglas  fir 6 

Spruce 6 

Western  pine 5 

White  pine 5 

Lodgepole  pine 5 

Tamarack 5 

Hemlock 5 

Red  oaks 4 

Beech 4 

Maple 4 

Gum , .  3 

Loblolly  pine 3 


20 
14 
15 
14 
17 
14 
16 
15 
15 
20 
20 
18 
16 
15 


11 
11 
11 
12 
10 
11 
11 
11 
12 
12 
12 
11 
10 


U.  S.  Dept.  of  Agriculture  Bull.  No.  118,  Nov.  9th,  1912. 


MECHANICAL  EQUIPMENT 


91 


The  approximate  cost  of  this  preservative  treatment  for  ties 
(7  in.  X  9  in.  X  8  ft.,  or  42  board  feet)  is  given  by  the  same 
authority  as  follows: 


Kind  of  treatment 

Cost  of  treatment 

Preservative 

Amount 
injected, 
Ibs.,  per 
cu.  ft. 

Season- 
ing 

Labor 

Fuel 

Mainte- 
nance 

Chemi- 
cals 

Total 

Creosote  

10 

$0.01 

$0.06 

$0.01 

$0.015 

$0.279 

$0.375 

Creosote  

6 

.01 

.06 

.01 

.015 

.168 

.263 

Zinc  chloride  .  . 

.5 

.01 

.06 

.01 

.016 

.070 

.166 

Creosote 
Zinc  chloride  j 

•3  ! 

•5   j 

.01 

.06 

.01 

.016 

.154 

.250 

The  economic  avantage  of  this  treatment  is  not  only  in  more 
than  doubling  the  life  of  the  tie,  but  in  sawing  the  cost  and  in- 
convenience of  replacement. 

The  care  of  ties  in  storage,  as  well  as  in  usage,  should  be  con- 
sidered. They  should  be  piled  in  open-crib  or  some  way  as 
to  be  well  ventilated  yet  protected  from  ground  water,  decayed 
grass,  weeds  and  wood.  The  piles  should  be  plainly  marked  and 
spaced  for  inspection  and  seasoning.  Zinc-treated  ties  must  not 
be  placed  in  service  until  they  have  seasoned  the  full  time  pre- 
scribed for  that  purpose. 

When  the  ties  are  placed  in  service,  note  that  the  year  rings  of 
growth  point  downward. 

The  use  of  tie-plates  is  of  great  importance  to].prevent  the  me- 
chanical wear  between  the  rail  and  the  tie. 

Frogs  and  Switches. — Standard  track  material  is  generally  used 
in  pit-work  and  can  be  secured  from  manufacturers  of  such  ma- 
terial to  suit  every  purpqse.  It  should  be  noted  that  for  frogs, 
switches  and  crossings  the  use  of  manganese-steel,  both  of  the 
insert  and  solid  type  design,  has  shown  great  economy  and  is 
strongly  recommended.  It  will  usually  be  found  more  satis- 
factory to  purchase  such  track  material  from  specialists  in  its 
manufacture  than  to  try  to  build  it  in  the  plant  shops.  A  full 
description  of  the  conditions  under  which  the  part  is  to  operate 
will  usually  result  in  securing  from  the  manufacturer  most  satis- 
factory designs  and  workmanship. 

There  has  never  been  any  question  about  the  life  of  a  spring- 
frog  as  compared  with  a  rigid-frog,  but  the  former  has  not  always 


92  STEAM  SHOVEL  MINING 

been  considered  safe.  Safe  designs  are  obtainable  now  and 
should  be  used  where  practicable. 

Guard-rails  are  usually  placed  opposite  frogs  on  one  or  both 
tracks.  They  are  usually  simply  spiked  and  braced,  or  may  be 
held  with  adjustable  clamps  and  division-blocks  and  bolts. 
Satisfactory  guard-rails  are  also  made  of  manganese-steel,  all 
in  one  piece,  with  braces,  spike-lugs  and  plates  ready  for  instal- 
lation.1 With  sharp  turnouts,  guards  are  recommended  to  be 
%  in.  higher  than  the  track  rail.  The  toe  end  of  a  frog  on  a 
curved  run  should  be  braced  with  shoulder-plate  or  track-brace 
on  the  first  two  or  three  ties  forward  of  the  %  in.  frog-point  to 
maintain  track  gauge.  These  require  but  little  upkeep. 

Very  rugged  frogs  are  also  manufactured  of  solid  manganese- 
steel  in  one  piece  and  with  wheel-flange  protective  flanges.2 
With  their  use  it  should  not  be  necessary  to  guard-rail  the  tangent 
track. 

The  split-switch  should  be  used  wherever  possible  though  stub 
and  lap  switches -may  sometimes  be  necessary.  The  switch 
should  be  well  reinforced  on  both  sides  of  the  web  by  bars,  or 
should  be  made  of  manganese-steel.  Where  the  points  are  well 
reinforced  it  is  not  necessary  to  have  more  than  two  bridle- 
rods,  and  the  rail  is  less  liable  to  fracture  or  part.  The  bridle- 
rods  may  be  attached  to  the  web  or  base  of  the  rail  by  bolts  or 
patented  safety  devices,  but  good  die-formed  clips  attached  to 
the  web  of  the  rail,  and  holding  the  rods  in  a  vertical  position,  are 
very  satisfactory.  The  head-rods  are  sometimes  made  adjusta- 
ble by  means  of  a  clevis  or  screw. 

Switch-stands  are  of  numerous  designs  ranging  from  simple 
ground-throw  stands  through  pony-stands  to  high  main-line 
stands,  or  even  the  high  ladder-stands.  Their  selection  is  largely 
a  matter  of  personal  choice  and  adaptability.  Stands  with 
single  targets  are  to  be  preferred  to  those  with  dual  targets  of 
different  colors. 

Protective  Devices. — These  should  be  employed  wherever  pos- 
sible when  danger  exists.  Crossing-bells  are  now  in  service  on 
most  railroads  and  are  reliable  both  day  and  night.  They  should 
possess  loud-ringing  bells  and  attractive  visual  signals  for  both 
day  and  night.  For  dangerous  curves,  switches  and  yards  where 
there  is  possibility  of  collision  or  accident,  block  signals  of  an 

1  Ajax  Forge  Company. 

2  Connelly  Frog  Company. 


MECHANICAL  EQUIPMENT  93 

approved  type  will  be  found  a  great  economy.  Safety  devices 
and  their  application  are  a  very  important  and  broad  subject  which 
cannot  be  but  touched  upon  here,  but  if  given  careful  study  by 
pit  operators  they  will  find  it  more  than  recompenses  every 
effort  they  make  in  safeguarding  their  men,  equipment  and  con- 
tinuous operation. 

DRILLS 

Preparation  of  the  ground  to  be  excavated  frequently  re- 
quires more  or  less  loosening  or  breaking  up  before  it  can  be 
efficiently  handled.  This  operation  is  usually  done  by  the  aid 
of  explosives  placed  most  advantageously.  The  drilling  of 
holes  to  accommodate  such  charges  of  explosives  is  one  of  the 
common  methods.  The  drills  used  for  this  work  may  be  divided 
into  two  classes,  viz.  churn  drills  and  piston  drills.  This  class 
of  drilling  is  not  to  be  confused  with  prospect  drilling. 

Churn-drills. — Churn  drills  have  to  a  large  extent  displaced 
the  tripod  piston  drills.  The  reason  is  that  it  has  been  found 
more  economical  to  sink  a  few  holes,  say,  6  in.  in  diameter 
to  the  full  depth  of  the  cutting,  say,  50  to  150  ft.,  than  to 
drill  a  large  number  of  small  shallow  holes  at  various  levels. 
This  has  generally  resulted  in  speeding  up  the  breakage  with 
all  attendant  economies  and  convenience,  and  also  in  greater 
safety.  In  some  cases  the  cost  of  drilling  and  explosives  have 
also  been  reduced.  By  this  method  benches  and  faces  are 
usually  broken  in  one  stage.  Churn  drills  are  best  adapted 
to  work  where  the  height  of  the  face  exceeds  25  ft.  and  where 
the  formation,  if  stratified,  is  more  or  less  flat.  Holes  5^  in. 
in  diameter  are  recommended  for  the  harder  rocks  because  more 
explosive  can  be  concentrated  in  the  bottom  of  the  hole,  where 
it  is  usually  most  needed,  and  the  larger  hole  permits  a  greater 
spacing  interval  and  thus  a  lesser  drilling  cost.  In  the  softer 
rocks,  such  as  shale  or  sandstone  and  even  some  limestones,  or 
when  working  a  shallow  face,  the  use  of  4  in.  or  4J^  in.  bit 
may  be  more  economical  because  distribution  of  the  charges 
rather  than  concentration  is  desired.  Thus  a  5%  in.  hole 
requires,  say,  15  Ib.  of  dynamite  per  foot  whereas  a  4  in.  hole 
requires  only  about  7^  Ib.  Economy  in  explosives  may  thus 
be  gained  where  the  conditions  warrant  the  lighter  charges. 

Drills  suitable  for  this  work  are  made  by  the  Keystone,  Star 
Cyclone  and  other  driller  companies.  They  range  in  sizes 


94  STEAM  SHOVEL  MINING 


from  those  drilling  holes  of  4J^  to  8  in.  in  diameter  and 
may  be  traction  or  non-traction,  and  steam,  gasoline  or  electric 
driven. 

For  general  blast  hole  work,  the  Keystone  steam  traction  size 
No.  3^,  drilling  a  5%  in.  hole,  is  well  suited;  for  very  light  work, 
the  non-traction  size  No.  1,  drilling  4J^  in.  holes,  will  serve; 
but  for  hard  usage  and  heavy  work  such  as  is  found  at  most  of 
the  copper  mines,  the  traction  size  No.  5,  drilling  a  6  in.  hole, 
will  be  found  most  serviceable. 

Selection  of  motive  power  will  depend  to  some  extent  on  local 
conditions,  as  steam,  electric  and  gasoline  driven  rigs  have  all 
been  satisfactorily  developed.  The  steam  drill  is  the  speediest, 
handiest  and  most  reliable,  but  presents  the  questions  of  water 
supply,  cost  of  fuel  and  fireman.  The  electric  drill  is  lighter, 
moves  about  under  its  own  power,  within  range  of  its  wiring, 
and  requires  no  fireman  or  fuel  and  water  care.  Cyclone  electric 
rigs  have  given  satisfactory  service  at  the  Chile  Copper  Com- 
pany's mines. 

The  gasoline  drill  has  many  of  the  advantages  of  the  two  former 
but  it  is  not  as  flexible  or  reliable.  Experience  with  gasoline 
engines  leads  to  this  conclusion.  In  some  cases  the  steam  rigs 
have  been  run  with  fair  success  by  compressed  air.  Every- 
thing considered  the  steam  traction  rig  is  most  widely  preferred. 

The  Keystone  No.  3J^  traction  steam  machine  weighs  about 
seven  tons  and  the  No.  5  about  nine  tons.  The  Star  drills  are 
heavier;  those  at  Utah  Copper  had  16  h.p.  engines  with  8  in. 
X8  in.  cylinders.  The  cranks  are  adjustable  but  run  on  about  18 
in.  stroke.  The  weight  of  the  tools  on  these  drills  is  2000 
Ib.  They  are  used  principally  for  prospect  drilling  and  not 
for  shallow  holes.  As  the  holes  drilled  on  this  work  are  compara- 
tively shallow  (50  to  150  ft.)  they  are  drilled  by  "  spudding." 
Jars  are  seldom  required,  consequently  the  strings  of  tools  are 
short  and  a  shorter  mast  may  be  used,  thereby  lowering  the  centre 
of  gravity.  On  some  works  it  has  been  found  advantageous 
to  convert  the  operating  rods  into  levers,  placing  them  on  the 
inside  of  the  bed;  the  walking  beams  have  been  reinforced  and 
the  spudding  wheels  on  the  beam  have  been  attached  to  I-beams; 
in  some  parts  cast-steel  has  been  substituted  for  cast-iron. 
Such  changes  have  been  made  to  withstand  rough  usage. 

Where  eight  or  ten  drills  are  employed  each  drill  carries  the 
following  equipment: 


MECHANICAL  EQUIPMENT  95 

200  feet  of  2-inch  manila  drill  cable  (hawser-laid) 
150  to  160  feet  of  %  in.  wire  sand-line. 
1 — standard  Keystone  rope-socket. 
1—4  in.  or  4>£  in.  X  20  ft.  drill-stern. 
1—5%  in.  No.  100  Mother  Hubbard  bit. 
1 — 12  ft.  sand-pump  (may  be  made  from  4^  in.  casing). 
1 — 10  in.  Keystone  steam-driven  blower  (with  steam  rigs). 
1 — forge,  consisting  of  a  pipe  2  in.  X  36  in.  and  a  wood  box  32  in.  X  36  in. 
1 — right-hand  tool  wrench  for  3%  in.  squares. 
1 — left-hand  tool  wrench  for  3%  in.  squares. 
1 — single-acting  floor-jack  and  circle. 
2 — No.  6  Barrett  lever  hoisting  jacks. 
1 — spectacles. 

1 — anvil  billet  and  block  (consists  of  a  piece  of  75  Ib.  rail  one  foot  long 
spiked  to  a  2  in.  X  12  in.  plank.) 

3  to  7 — 50-gallon  water  barrels  (3  used  in  summer  and  7  used  in  winter). 

2 — gasoline  torches. 

2 — 16-lb.  sledge  hammers. 

1 — set  small  tools,  such  as  machinist  hammers,  wrenches,  files,  oilers,  etc. 

Such  small  repair  parts  as  extra  water  glasses,  gaskets,  pipe- 
fittings,  etc.  are  usually  kept  on  hand,  as  well  as  a  fair  amount 
of  extra  tools,  spare  parts  and  casing. 

It  has  been  found  that  200  feet  of  drill  cable  is  the  best  length. 
At  least  125  feet  are  needed  if  the  mast  is  to  be  lowered  or  raised. 
The  rope  will  wear  most  where  it  is  in  contact  with  the  spudding 
pulleys  and  sheave  pulley,  and  in  time  must  be  spliced.  Three 
splices  will  shorten  the  rope  about  40  feet.  After  a  rope  has 
been  worn  out  there  is  about  60  feet  of  good  rope  left  on  the 
drum,  and  generally  this  60  feet  can  be  spliced  on  to  a  rope  having 
three  or  four  splices,  making  a  practically  new  rope  for  that  rig 
while  the  other  drill  receives  a  new. rope.  In  this  way  much 
valuable  rope  can  be  saved. 

The  drilling  crew  consists  of  one  driller  and  one  tool-dresser. 

Coal  is  supplied  to  the  drills  from  piles  conveniently  placed 
along  the  benches. 

When  a  drill  must  be  moved  from  one  bench  to  another,  or  for  a 
considerable  distance,  much  time  may  be  saved  and  wear  on  the 
drill  avoided  by  loading  the  drill  onto  a  flat  car  by  means  of  a 
locomotive  crane.  This  is  illustrated  in  Fig.  17  at  the  Nevada 
Consolidated  Copper  Company.  To  do  this,  three  chains  of 
proper  length  are  attached  to  the  drill,  one  just  above  the  front 
axle  and  the  other  two  to  the  two  rear  wheels.  The  mast  is  not 
lowered  nor  are  the  tools  taken  off  the  machine;  the  fire  is  not 
drawn  nor  is  the  boiler  blown  out.  A  barrel  of  water  is  put  on  the 


96 


STEAM  SHOVEL  MINING 


bed  of  the  drill  and  all  other  equipment  is  loaded  on  the  flat  car. 
When  the  drill  is  unloaded  it  moves  to  its  new  spot  and  begins 
drilling.  The  barrel  of  water  serves  until  the  necessary  water 
connections  are  made. 

This  method  obviates  preparing  a  road;  requires  but  3  men 
on  the  crane  beside  the  drill  crew,  instead  of  at  least  10  men  on 
roads  and  moving;  causes  no  delays  or  damage  on  haulage 
tracks  passed  over  or  along;  and  relieves  the  drill  of  most  of 
the  wear  and  tear  of  moving.  When  it  is  necessary  to  move  a 
drill  on  its  own  power,  the  tools  are  tied  beneath  the  rig  and 


FIG.  17. — Moving  drill  with  locomotive  crane. 

dragged  along  the  ground;  a  barrel  of  water  is  put  on  the  bed  of 
the  machine  and  the  remainder  of  the  equipment  is  carted  along 
on  a  push  car  or  by  teams. 

These  drills  carry  a  working  steam  pressure  of  100  Ib.  per 
sq.  in.  They  consume  per  shift  about  600  Ib.  of  coal,  twelve 
50-gallon  barrels  of  water  (for  boiler  and  drill  hole);  1J£  pints 
of  cylinder  oil;  1  pint  dark  lubricating  oil;  %  Ib.  cup  grease;  J^ 
gallon  of  gasoline  for  night  lighting;  and  Ji  Ib.  cotton  waste. 

With  hard  mining  usage  they  require  many  renewals  and 


MECHANICAL  EQUIPMENT 


97 


repairs  but  by  a  little  careful  study  the  weaker  parts  can  be 
strengthened  by  increasing  their  size  or  changing  the  material. 
Repairs  are  made  in  the  field  until  the  drill  loses  its  efficiency, 
when  it  is  taken  to  a  shop,  entirely  dismantled,  examined  and 
rebuilt. 

The  footage  drilled  and  cost  per  foot  of  this  work  has  been 
found  to  be  about  as  follows: 


Character  of  ground 

Footage 
per  10  hr. 
shift 

Average 
depth    of 
holes,    ft. 

Average  cost 
per  ft. 

Soft  altered  porphyry  

60 

20-60 

25£  to  35?f 

Harder  altered  porphyry          ...        .    . 

40 

25-60 

35£  to  40£ 

Cement  quarry  limestone 

40 

45-70 

25  i  to  30^ 

Flat  limestone  

35 

50 

30?<  to  40?f 

Hard  trap  or  granite                         .    . 

20 

50 

40?f  to  60ff 

Under  average  conditions  these  drills  should  make  30  ft.  per 
shift  at  a  cost  of  30  cents  per  foot. 

The  percentage  of  time  in  drilling  may  be  estimated  at  85 
per  cent. ;  in  moving  5  per  cent.;  in  repairing  and  other  stoppages, 
10  per  cent.  About  75  per  cent,  of  the  cost  is  for  labor  and  25 
per  cent,  is  for  supplies.  Keystone  drills,  sizes  3J^  and  5  steam 
tractors,  cost  about  $1200  and  $1400  each  respectively  at  the 
factory. 

Tripod  Drills. — Tripod  drills  are  used  in  cases  where  relatively 
shallow  holes  with  light  powder  charges  are  best  suited;  where 
benches  are  too  narrow  for  the  use  of  churn  drills;  where  it  is 
necessary  to  shoot  the  toes  of  high  banks,  or  midway  points  in 
such  banks.  Such  holes  may  be  drilled  at  any  angle,  whereas  the 
churn  drill  hole  must,  of  course,  be  vertical.  These  holes  average 
about  1%  in.  in  diameter  and  run  from  10  to  25  feet  in  depth. 
The  drills  may  be  operated  by  air  or  steam;  single  or  in  batteries. 
They  are  built  by  the  Ingersoll-Rand,  Sullivan,  Denver,  Rock- 
hill  and  other  rock  drill  manufacturers.  The  care  of  the  drills 
and  steel  is  the  same  as  for  underground  practice. 

Both  the  reciprocating  piston  machines  and  the  hammer  or 
Leyner  type  are  used.  The  latter  require  a  water-feed  attach- 
ment but  are  faster  drillers.  The  18-A  and  248  Leyners  and  the 
Waugh  Turbo  are  the  newest  examples  of  the  hammer  and  turbo 
types.  The  18-A  costs  about  $255,  the  248  about  $335  and  the 
Turbo  about  $360,  without  tripods  or  steel. 


98  STEAM  SHOVEL  MINING 

The  cost  of  drilling  ranges  from  10  to  25  cents  per  foot  depend- 
ing on  the  character  of  rock,  costs  of  labor,  fuel  or  power,  oil, 
etc.,  number  of  drills  in  operation  and  nearness  to  source  of  power 
and  water.  The  fewer  the  drills,  the  higher  is  apt  to  be  the  cost 
per  foot.  The  footage  made  per  10  hr.  shift  ranges  from  40 
to  60  ft.  in  rocks  of  medium  hardness,  such  as  limestone,  and 
from  20  to  30  ft.  in  traps  and  granites. 

Large  drills  of  the  piston  type  have  been  specially  built  for  some 
companies,  notably  at  Rio  Tinto,  Spain,  where  slope  holes  were 
necessary.  These  special  machines  are  very  heavy  and  powerful, 
suitable  for  drilling  2-in.  holes  to  depths  of  25  ft.  or  more.  They 
are  moved  about  on  push  cars. 

In  operating  drills  of  this  type  power  is  supplied  them  by  a 
central  compressor  plant  with  attendant  air  lines  or  by  steam 
boilers  near  the  drills;  long  steam  lines  are  inefficient.  Electric 
drills,  with  the  exception  of  the  Temple-Ingersoll,  have  not  been 
sufficiently  perfected  for  this  service. 

Drills  for  Block-holing. — After  a  bank  has  been  shot,  there 
frequently  remain  many  fragments  or  boulders  too  large  to  be 
handled  by  the  shovels.  Again  it  sometimes  happens  that  a 
hole  will  not  completely  break  the  bottom  of  the  bench,  so  that 
it  must  be  further  shaken  up. 

For  this  work  powder  may  be  placed  directly  on  the  face  of  a 
boulder  or  " bottom,"  covered  with  mud  or  dirt  and  exploded; 
or  holes  may  be  drilled  in  the  face  and  the  powder  charged  as 
usual.  The  former  method  is  called  " mud-capping,"  "doby- 
ing,"  " bull-dozing"  or  "burning  bottom, "  and  the  latter  " block- 
holing."  ;i 

Block-holing  is  much  more  effective  and  economical  in  powder 
but  may  not  be  desirable  for  other  reasons.  If  block-holing  is 
found  advantageous  the  drilling  may  be  done  by  hand  or  with  light 
plugging  or  rotating  drills.  Of  these  small  drills  the  Jackham- 
mer  BCR  is  the  most  satisfactory.  In  case  no  air  or  steam  line 
is  available,  it  is  an  easy  job  to  equip  the  shovels  with  a  small 
air  compressor  similar  to  those  used  for  locomotive  train  service. 
These  have  a  capacity  of  150  cu.  ft.  free  air  per  minute,  are  en- 
tirely self-contained  and  will  operate  three  Jackhammer  drills. 
The  outfit  supplied  by  the  Westinghouse-Pacific  Coast  Brake 
Company  is  made  up  as  follows: 

One  10J£  in.  cross  compound  air  compressor;  one  S-6  gover- 
nor; one  sight-feed  lubricator;  1J£  in.  steam  valve;  one  reservoir 


MECHANICAL  EQUIPMENT  99 

drain  cock;  one  air  gauge;  one  30^  in.  X  72  in.  reservoir;  one 
compressor  stand.  The  cost  of  the  outfit  is  about  $400. 

The  BCRW  Jackhammer  drills  cost  about  $140  each. 

Such  equipment  is  recommended  where  local  conditions  do  riot 
interfere. 

MISCELLANEOUS  EQUIPMENT 

Pumps. — In  many  open-pit  mines  arrangements  must  be  made 
to  take  care  of  more  or  less  surface  and  ground  water. 

Pumps  are  generally  employed  for  dewatering  simple  pit 
sumps.  In  some  instances  in  the  Lake  Superior  iron  ore  pits, 
a  system  of  drainage  drifts  is  run  beneath  the  pit.  These  lead 
to  a  pump  shaft  on  the  edge  of  the  pit.  Such  pits  often  handle 
from  500,000  to  2,000,000  gal.  of  water  per  day.  As  pits 
increase  in  size  and  depth,  the  water  to  be  handled  is  likely  to 
increase.  There  is  usually  a  wet  season  to  contend  with,  and 
in  some  instances  even  cloud  bursts  have  occurred  which  have 
done  considerable  damage  to  the  workings  and  equipment. 
Again,  as  in  the  case  of  copper  mines,  the  pit  waters  may  be 
very  corrosive,  necessitating  pre-treatment  or  special  pipe  lines 
and  equipment.  All  of  these  points  must  be  considered  in  deter- 
mining what  dewatering  equipment  will  be  required.  With  a 
fair  idea  of  the  quantity,  lift  and  nature  of  water  to  be  handled, 
any  of  the  better  known  pump  makers  will  be  able  to  advise  the 
most  suitable  equipment  for  the  work.  With  a  little  care  a  pit 
drainage  system  can  generally  be  so  arranged  that  the  pumps  and 
pipe  lines  will  require  but  little  shifting  and  may  be  given  more 
care  in  installation.  Electric  power,  if  available,  is  usually  by 
far  the  most  economical  and  satisfactory.  Whether  the  pumps 
be  centrifugal  or  reciprocating,  geared  or  belted,  will  depend  on 
local  conditions.  Some  sort  of  housing  should  be  provided  for 
them  and  reasonable  care  given  to  lubrication  and  repair.  For 
short  temporary  work  a  light  pump  mounted  on  a  wheeled  bed 
is  very  convenient. 

Illumination  for  Night  Work. — Most  open  pit  mines  are  required 
to  work  night  shifts  in  order  to  fulfill  production  requirements. 
When  this  is  the  case,  the  problem  of  adequate  illumination  must 
be  carefully  considered. 

Permanent  locations  about  the  property  will  usually  be  served 
with  modern  electric  incandescent  outdoor-type  -equipment. 
For  less  permanent  locations,  such  as  along  edges  of  dumps, 


100  STEAM  SHOVEL  MINING 

movable  incandescent  electric  light  tripod  stands,  built  of  light 
pipe  and  served  with  flexible  armoured  cable,  will  be  found  very 
convenient.  These  stands  should  be  about  14  ft.  high  and  carry 
one  100  c.p.  lamp,  with  open  reflector,  at  the  goose  neck.  The 
frequency  or  spacing  of  the  stands  will  depend  on  dumping 
conditions,  but  there  should  be  sufficient  of  them  to  enable  the 
workmen  to  move  about  with  safety.  Flood  lights  may  at  times 
be  used  to  advantage  if  properly  placed  and  mounted.  Current 
for  all  of  this  lighting  equipment  is  presumed  to  come  from 
the  general  property  circuit. 

For  night  work  with  the  shovels,  adequate  illumination  is 
imperative,  not  only  on  the  bank  from  which  the  shovel  digs, 
but  around  the  shovels  themselves,  to  permit  inspection  and 
adjustment  and  to  afford  safety  to  the  workmen.  Acetylene 
was  first  used  but  in  comparison  with  electricity,  it  has  been 
found  more  troublesome,  costly,  and  less  safe.  At  one  time 
the  Utah  Copper  Company  illuminated  its  benches  by  three 
powerful  searchlights  set  on  the  opposite  side  of  the  canyon. 
Current  for  this  lighting  may  be  taken  from  local  pole  lines 
through  a  reeled  cable  to  the  shovel,  but  from  the  nature  of  the 
work  such  lines  will  be  troublesome  to  maintain,  and  the  voltage 
is  usually  higher  than  that  desired  for  use  with  incandescent 
lamps  having  the  toughest  filament.  A  better  means  of  sup- 
plying current  is  to  mount  a  1  KW.  turbo-generator  outfit  in  a 
convenient  place  on  the  shovel,  and  drive  it  with  steam  from 
the  boiler.  One  of  these  sets  will  operate  about  forty  25-watt 
incandescent  lamps  or  their  equivalent.  They  require  little 
attention  and  are  rugged  and  accessible  for  inspection.  They 
operate  to  full  rating  with  steam  pressures  between  90  and 
250  Ib.  A  governor  keeps  the  speed  uniform  and  the  light 
steady.  A  fixed  resistance  regulates  the  voltage  and  a  rheostat 
is  provided  to  adjust  the  voltage  when  the  number  of  lamps 
is  varied. 

A  comparison  on  one  property  of  the  relative  cost  of  lighting 
with  acetylene  and  by  these  turbo-generators,  was  estimated 
as  follows : 
Carbide:  Average  carbide  used  per  steam  shovel  per  month; 

2800  Ib.  at  $.0415  =  $116.20 

1  KW.  turbo-generator:  Average  steam  consumption  200  Ib. 
per  hr.  at  6%  Ib.  per  Ib.  of  coal  =  30  Ib.  coal  per  hr.,  at 


MECHANICAL  EQ  UIPMENT  -101 

9  hr.  X  30  shifts  =  8100  Ib.  or  4.05  tons,  at  $5.65  =  $22.88 
per  month. 

In  both  cases  attention  and  maintenance  must  be  added,  and 
the  carbide  plant  requires  more  care. 

For  locomotive  lighting  the  same  arguments  may  be  applied. 
A  turbo-generator  of  J<j  KW.  is  sufficient  for  illumination. 
This  will  supply  current  for  a  250-watt  incandescent  headlight 
plus  4  cab  lamps,  or  two  150-watt  headlights  plus  2  cab  lamps. 
The  steam  consumption  at  this  load  is  about  90  Ib.  per  hr. 
The  voltage  regulation  is  entirely  satisfactory.  A  running 
test  with  these  headlights  gave  a  distance  of  705  ft.  with  the  150- 
watt  lamp,  and  1163  ft.  with  the  250-watt  lamp.  The  test 
was  made  at  31  volts;  weather  conditions  favorable. 

The  cost  of  operating  carbide  lights  compared  to  the  turbo- 
generator was  estimated  as  follows: 

Carbide:  Average  use   per   locomotive   per  month,  232  Ib.  at 
$0.415  =  $9.63. 

^  kw.  turbo-generator:  Average  steam  consumption  90  Ib. 
per  hr.  at  6  Ib.  per  Ib.  of  coal  =  15  Ib.  coal  1  hr.,  at  9  hr. 
X  30  shifts  =  4050  Ib.  or  2.025  tons,  at  $5.65  =  $11.44  per 
month. 

Attention  and  maintenance  must  be  added  in  both  cases. 

The  cost  of  the  1  KW.  unit  is  about  $125  plus  lamps,  plus 
$20.  for  attachment  case.  The  J£  KW.  unit  costs  about 
$75.  The  Westinghouse  Electric  and  Schroeder  Headlight 
Companies  manufacture  such  units. 

Illumination  for  drill  rigs  is  usually  with  acetylene  or  gasoline 
torches,  the  latter  being  preferred. 

Telephones  and  Signals. — It  will  be  found  well  worth  while  to 
have  an  adequate  telephone  system  covering  all  principal 
outdoor  and  indoor  operations.  This  class  of  mining  usually 
covers  so  much  ground  that  means  of  quick  communication  is 
very  desirable  for  efficiency  and  safety  of  operation.  The 
location  of  the  telephones  must  be  left  to  the  good  judgment  of 
the  management.  An  efficiently  operated  central  switch-board 
is  very  desirable  and  should  be  "on  duty"  at  all  times.  Some 
installations  using  automatic  telephones  have  been  quite  satis- 
factory, but  it  is  questionable  whether  they  show  much  economy 
in  operation  over  the  manual  board  for  work  of  this  kind.  Care 
should  be  given  in  the  selection  of  instruments  exposed  to  the 
weather.  High-class  boards,  lines,  cables  and  instruments  will 


102  l  STEAM  SHOVEL  MINING 

be  cheapest  to  maintain  and  most  satisfactory  in  the  long  run. 
It  is  well  to  allow  for  additions  and  extensions  when  installing 
equipment.  Such  companies  as  the  Western  Electric  and  Trom- 
berg  Carlson  are  prepared  to  study  conditions  and  supply  or 
install  such  equipment. 

In  this  connection  note  that  fire  or  accident  sirens  may  be  so 
installed  as  to  be  operated  directly  or  indirectly  from  the  tele- 
phone central  in  case  of  emergency. 

Locomotive  Crane. — One  or  two  self-propelling  locomotive- 
cranes  of  about  30  tons  capacity  will  be  found  indispensable 
for  clearing  up  wrecks,  unloading  and  loading  coal  machinery 
and  supplies,  moving  drills  and  much  other  work.  For  heavy 
work  a  short  goose-neck  boom  should  be  provided,  also  clam-shell 
and  orange-peel  buckets.  These  machines  are  useful  in  doing 
a  certain  amount  of  excavation  work  where  the  cut  is  too  shallow 
or  the  job  too  small  for  a  shovel.  Such  jobs  would  be  slower 
and  more  expensive  if  done  by  hand. 

Dump  Plows. — These  have  been  profitably  used  in  dump 
building  on  the  Mesabi.  They  vary  in  size  from  those  having  a 
a  spread  of  5  feet,  called  "  dozers,"  to  large  dump  spreaders  which 
cut  18  to  24  inches  below  the  dump  track  and  distribute  the 
dirt  for  a  width  of  20  to  30  ft. 

Repair  Car. — A  master  mechanic's  repair  car  will  be  found  of 
great  convenience  in  going  about  the  pits  making  repairs  to 
shovels  and  washing  out  boilers  on  the  job.  In  this  way  such 
equipment  will  not  have  to  be  brought  into  the  shops,  except 
for  general  overhaul,  and  a  saving  in  time  can  be  affected  in 
much  of  the  repair  and  upkeep  work. 

The  following  equipment  fitted  into  an  ordinary  box  car 
with  two-ton  coal  bunker  will  be  found  satisfactory. 

1 — 25  hp.  Economy  boiler,  return  flue,  equipped  with  one  3^  in.  and  one 
1  in.  injector. 

1 — 10^  in.  cross-compound  air-compressor,  with  air  receiver  24  in.  dia. 
by  48  in.  long. 

1 — air  motor  for  drilling  and  boring. 

1 — air  hammer. 

1 — Vulcan  welding  outfit  complete. 

1 — 6  in.  vise  and  1 — 3  in.  pipe-vise  fitted  on  work  bench. 

1 — 3^  in.  X  4  in.  X  33^  in.  duplex  water  pump. 

1 — hand  drill-press. 

1 — 1  ton  and  1 — 2%  ton  chain  blocks. 

2 — 50  ton  Norton  jacks  and  2 — 15  ton  Barrett  jacks. 


MECHANICAL  EQUIPMENT  103 

2 — 12  in.  and  2 — 6  in.  screw-jacks. 

Hose  and  nozzles  for  boiler  washing. 

Such  miscellaneous  hand-tools  as  wrenches,  hammers,  chisels,  etc. 

Employees  Car. — Time  may  be  saved  in  getting  crews  to  work 
by  fitting  up  a  car  to  distribute  and  collect  them  at  their  points 
of  work.  By  this  means,  they  may  be  brought  in  from  work  to  a 
central  mess  point  where  a  hot  lunch  is  provided.  For  this 
purpose  a  box  car,  fitted  with  a  stove,  benches  and  straps,  and 
hauled  about  by  one  of  the  locomotives,  is  often  of  considerable 
convenience. 

Coaling  Car. — A  specially  designed  steel  coaling  car  may  be 
provided  so  that  after  loading  from  a  coal  stock  pile  by  means  of  a 
clam  shell,  it  can  be  run  around  to  the  different  shovel  points, 
and  a  shift  of  coal  drawn  from  it  from  side  chutes. 

Powder  Cars. — Cars  of  the  refrigerator  type  may  be  employed 
to  distribute  powder  from  magazines  to  the  blasting  points. 
In  such  a  car  the  powder  will  be  kept  in  proper  thawed  condition 
in  the  coldest  weather,  until^it  is  actually  required  for  loading. 
In  warmer  weather  a  flat  car  covered  with  a  tarpaulin  may  be 
used  for  explosive  distribution. 

General  Utility  Cars. — From  four  to  six  flat  cars  will  be  found 
handy  for  transporting  all  sorts  of  parts  and  materials  to  and 
from  the  works.  Two  or  three  light  four-wheel  push-cars 
should  also  be  provided. 

Wagons  and  Trucks. — Some  means  of  transportation  must  be 
provided  for  distributing  materials  to  points  not  accessible  by 
rail.  Where  the  haul  is  fairly  long  and  the  roads  fairly  good, 
motor  trucks  can  be  employed  to  advantage.  Where  the  haul 
from  rail  to  such  points  is  comparatively  short  or  the  roads 
very  poor,  teams  and  wagons  may  prove  more  satisfactory  and 
the  cost  of  operation  cheaper.  At  some  properties  both  methods 
are  used  because  of  varied  local  conditions. 

Shops. — Well  equipped  adequate  work  shops  are  the  principal 
tools  with  which  operations  are  carried  on.  They  should  be 
planned  with  much  care  and  then  built  and  equipped  as  early 
in  the  construction  period  as  possible.  They  will  then  be  avail- 
able to  serve  during  the  construction  and  opening  up  period  as 
well  as  later  Their  importance  is  secondary  only  to  the  proper 
housing  and  care-taking  of  the  operating  personnel. 

For  shovel  mines  there  are  required  machine,  blacksmith,  engine 
and  car,  electrician  and  carpenter  shops.  For  a  property  pro- 


104  STEAM  SHOVEL  MINING 

ducing  say  from  10,000  to  20,000  tons  per  day  the  following 
equipment  should  prove  adequate. 

Machine  Shop. — The  building  will  have  a  floor  plan  of,  say  120 
ft.  X  180  ft.,  steel  construction,  well  lighted,  heated  and  venti- 
lated, and  will  be  served  with  single  or  double  track  connections 
from  the  outside.  It  will  be  equipped  with  modern  tools.  In- 
dividual electric  drive  is  for  the  most  part  preferred.  The 
makes  of  tool  are  optional  and  subject  to  personal  opinion  but 
those  given  will  be  found  satisfactory.  It  is  best  to  see  that  lists 
drawn  are  up  to  date  as  the  following  list  is  intended  to  be  sug- 
gestive only. 

1 — 25  ton  capacity  travelling  crane  with  50  ft.  to  60  ft.  span,  and  with  a 
5-ton  auxiliary  hoist.  N.  B.  P.  Co. 

1 — air  compressor  500  cu.  ft.  min.  class  P.  E.  2  I-R  Co.,  motor  driven. 

1 — high  pressure  blower — motor  driven  No.  4  B.  F.  S.  Co.,  with  suitable 
reservoir. 

1 — 1100-lb.  single  frame  steam  (or  air)  hammer  with  cast  steel  anvil  and 
anvil  cap.  No.  1518  N.  B.  P.  Co. 

1 — 1^  in.  head  and  forging  machine  for  bolts,  rivets  and  small  forgings. 
A.  M.  Co. 

1 — bending  rolls,  capacity  10  ft.  wide  X  1  in.  thick.  Motor  driven  with 
separate  motor  for  vertical  adjustment  of  top  roll.  Size  No.  7  N.f B.  P.  Co. 

1 — bending  rolls  "pinching  type"  capacity  6  ft.  wide  by  J£  in.  thick. 
N.  B.  P.  Co.  size  No.  1. 

1 — plate  flanging  clamp  12  ft.  X  4  in.,  to  be  raised,  lowered  and  clamped 
by  air.  N.  B.  P.  Co. 

1 — 48  in.  double  punch  and  shears.     Size  No.  1  L.  &  A.  Co. 

1 — bar  cold  saw  cutting-off  machine,  high  duty  type,  36  in.  blade  with 
regular  clamps  and  air  clamps,  with  automatic  saw  sharpening  machine 
No.  2471;  No.  503  N.  M.  T.  Co. 

2 — patent  inserted  tooth  milling  saws  with  high  speed  teeth  fine  pitch  for 
structural  iron.  H.  B.  S.  M.  Co. 

1 — ditto  with  teeth  coarse  pitch  for  bar  iron.     H.  B.  S.  M.  Co. 

1 — 100- ton  hydraulic  forcing  press,  to  be  operated  by  hand;  used  in  a  pit 
4  ft.  deep  X  6  ft.  wide  X  30  ft.  long;  used  to  straighten  car  doors,  dipper 
sticks,  car  sills,  I-beams  and  any  large  long  pieces.  V.  I.  W.  Co. 

1 — 96  in.  400-ton  hydraulic  driving-wheel  press,  inclined  type  N.  B.  P.  Co. 

1—3  hp.  U.  S.  grinding  stand;  U.  S.  E.  T.  Co. 

1 — 5  hp.  floor  grinder. 

1 — arbor  press,  No.  6  G.  T.  E.  Co. 

1 — Economy  power  saw,  No.  4.     W.  R.  M.  &  F.  Co. 

1 — 6  in.  pipe  threading  and  cutting  machine  with  standard  equipment. 
L.  M.  Co. 

1 — 2^  in.  double  bolt  cutter,  equipped  with  lead  screw  on  one  side. 
A.  M.  Co . 

1 — 2  in.  double  bolt  cutter  without  lead  screw.     A.  M.  Co. 


MECHANICAL  EQUIPMENT  105 

1 — 24  to  36  in.  upright  special  pattern,  shaft  driven  high  speed  drill  with 
tapping  attachment,  round  table,  variable  speed  motor  drive.  C.  P.  T.  Co. 

1 — 28  in.  upright  high  speed  shaft  driven  drill,  round  table  tapping  at- 
tachment. C.  P.  T.  Co. 

1 — 5  ft.  high  speed  full  universal  radial  drill.     A.  T.  W.  Co. 

1—7  ft.  high  speed  full  universal  radial  drill.     A.  T.  W.  Co. 

1 — 25  in.  crank  shaper.     S.  &  M.  Co. 

1 — 42  in.  standard  planer,  10  ft.  table,  with  inside  heads,  reversing  motor 
drive.  N.  B.  P.  Co. 

1 — No.  5  universal  high  power  milling  machine — motor  driven  by  silent 
chain.  14  in.  universal  dividing  head.  Plain  vise.  Toolmakers  universal 
vice.  All  steel  machine,  vice  10  in.  X  2  in.,  oil  pump,  and  the  following 
arbors:  90-B,  91-G,  92-G,  93-J,  94-J,  95-J,  96-J,  101-J,  102-J,  103-J, 
209-A,  210-A,  211-A,  212-A,  2'13-F  and  232-A.  Shell  end  mills:  401,  403, 
405,  407,  410,  412,  601,  602,  603,  604,  605  and  one  12  in.  standard  face 
mill.  C.  M.  M.  Co. 

1 — universal  grinding  machine  for  grinding  all  kinds  of  tools  and  cutters. 

1 — 36  in.  20  ft.  bed,  selective  head  standard  engine  lathe,  taper  attach- 
ment, steady  and  follower  rests.  • 

1—24  in.,  16  ft.  bed,  ditto  lathe. 

3—20  in.,  12  ft.,  bed,  ditto  lathes. 

1 — 20  in.,  10  ft.  bed,  ditto  lathe. 

Above  Lathes  by  L.  &  S.  M.  T.  Co. 

1 — 36  in.  all  steel  independent  lathe  chuck. 

1 — 24  in.  all  steel  independent  lathe  chuck. 

1 — 22  in.  all  steel  independent  lathe  chuck. 

4 — 18  in.  all  steel  independent  lathe  chucks. 

The  24  and  36  in.  chucks  for  36  in.  lathe— U.  M.  Co. 

If  locomotive  tire  turning  is  to  be  done  by  the  mine,  and  not 
at  some  railroad  shops,  a  wheel  lathe  of  a  size  to  do  the  work 
will  be  required.  This  is  an  expensive  tool  but  can  be  used  for 
special  large  work  not  accomodated  by  the  36-in.  lathe.  N. 
B.  P.  Co.  Omitting  the  wheel  lathe,  a  boring  mill  can  be  used 
for  large  work  but  not  as  broadly. 

For  the  blacksmith  shop,  add  a  forging  press.  This  will  be 
found  especially  useful  and  economical  in  making  bolts,  grab- 
irons  and  numerous  other  similar  parts. 

The  foregoing  only  includes  the  large  tools;  there  are  a  great 
many  small  tools,  including  pneumatic  riveters,  which  should 
be  selected  by  the  shop  foreman  or  master  mechanic,  but  need 
not  be  listed  here. 

REFERENCES: 

N.  B.  P.  Co.— Niles  Bement  Pond  Co.  N.  Y.  C. 

I.  R.  Co.— Ingersoll-Rand  Co.,  N.  Y.  C. 

B,  F,  g.  Co.— B.  F.  Sturtevant  Co.,  Boston,  Mass. 


106  STEAM  SHOVEL  MINING 

A.  M.  Co. — Acme  Machine  Co.,  Cleveland,  O. 

L.  &  A.  Co. — Long  &  Allstatter  Co.,  Hamilton,  O. 

N.  M.  T.  Co.  Newton  Machine  Tool  Co.,  Philadelphia,  Pa. 

H.  B.  S.  M.  Co— Huther  Bros.  Saw  Mfg.  Co.,  Rochester,  N.  Y. 

V.  I.  Co.— Vulcan  Iron  Works,  Chicago,  111. 

U.  S.  E.  T.  Co.— U.  S.  Electric  Tool  Co.,  Cincinnati,  Ohio. 

G.  T.  E.  Co. — G.  T.  Eames  Co.,  Kalamazoo,  Mich. 

W.  R.  M.  &  F.   Co. — W.  Robertson  Machine  &  Foundry  Co.,   Buffalo, 

N.  Y. 

L.  M.  Co. — Landis  Machine  Co.,  Waynesboro,  Pa. 
C.  P.  T.  Co. — Cincinnati  Pickford  Tool  Co.,  Cincinnati,  O. 
A.  T.  W.  Co.— American  Tool  Works,  Co. 
S.  &  M.  Co.— Smith  &  Mills  Co.,  Cincinnati,  O. 
C.  M.  M.  Co. — Cincinnati  Milling  Machinery  Co.,  Cincinnati,  O. 
L.  &  S.  M.  T.  Co.— Lodge  &  Shipley  Machine  Tool  Co.,  Cincinnati,  O. 
U.  M.  Co. — Union  Manufacturing  Co.,  New.  Britain,  Conn. 

Blacksmith  shop  and  forge. — This  may  be  conveniently  placed 
adjoining  the. machine  shop  but  should  be  partitioned  off  in 
such  a  way  as  to  prevent  dirt  and  smoke  from  passing  into  the 
machine  shop,  yet  affording  easy  communication  for  transfering 
parts  under  repair.  The  railroad  track  should  extend  into  the 
forge.  The  steam  hammer  may  be  placed  in  this  shop  or  a 
second  one  provided.  The  forging  press  above  mentioned  will 
be  placed  in  this  shop.  It  will  contain  four  or  five  forges,  blown 
with  low  pressure  air  and  served  with  one  or  two  crawls  with 
chain-blocks  for  supporting  heavy  work.  There  will  be  pro- 
vided bench  room  with  all  necessary  vises  and  hand  tools.  Con- 
venience in  storage  and  handling  coke  and  coal  will  be  considered. 
An  oxy-acetylene  welding  outfit  should  be  provided.  In  case 
tripod  rock-drill  equipment  is  to  be  used  provision  must  be  made 
for  the  testing  and  repair  of  the  machines  and  for  the  forming 
and  sharpening  of  the  drill  bits.  This  equipment  may  include 
a  Paynter  drill  testing  machine,  bit  muffle-roasters  and  automatic 
drill  sharpeners. 

Engine  and  car  shops. — The  first  may  be  planned  to  house  and 
repair  motive  power  and  the  second  to  overhaul  and  repair 
rolling  stock.  Both  will  be  provided  with  the  necesary  tracks 
repair  pits  and  should  be  served  with  a  suitable  crane.  Few 
tools  are  required  in  these  shops  because  most  of  the  work  will 
be  done  in  the  machine,  forge  and  wood  shops.  A  flue  cleaner, 
pipe  and  machinist's  vices,  screw-jacks,  hose  and  nozzles  for 
boiler  washing  and  miscellaneous  hand-tools  such  as  wrenches, 
hammers,  chisels,  etc.,  will  be  provided.  A  sand  house  should 


MECHANICAL  EQUIPMENT  107 

be  located  near  the  engine  shop     Here  sand  will  be  dried  and 
kept  ready  for  use. 

Electricians'  shop. — The  size  and  equipment  of  this  shop  will 
largely  depend  on  the  quantity  and  type  of  electric  equipment 
used  on  the  job.  Even  where  this  equipment  is  limited  some 
space  should  be  alloted  to  this  work  and  the  installation  should 
be  considered  by  the  chief  electrician. 

Carpenter  shop. — This  shop  will  take  care  of  woodworking  and 
wood  repairs.  It  will  be  convenient  to  have  the  following  equip- 
ment: Universal  woodworking  machine,  band  saw,  circular  saw 
table,  swing  cut-off  saw,  grindstone,  band  saw  sharpener,  and  an 
assortment  of  hand  and  bench  tools.  Care  will  be  given  to  the 
wiring  and  drives  of  the  machines  to  avoid  fire  risk. 

Foundry. — At  some  isolated  properties  it  has  been  found 
economical  to  put  in  a  foundry  for  the  casting  of  iron,  brass  and 
other  parts.  If  such  a  plant  is  deemed  advisable  it  should  be 
planned  by  the  master  mechanic  and  a  capable  foundryman. 

Sampling  and  assaying. — Equipment  will  not  be  detailed  here 
because,  while  important,  it  is  a  subject  belonging  to  mining  in 
general,  and  not  power-shovel  work  in  particular.  The  same  may 
be  said  of  engineering  and  surveying  paraphernalia.  In  the 
case  of  bank  sampling,  the  assay  laboratory  should  be  prepared 
to  make  quick  returns  as  they  may  govern  the  classification  and 
routing  of  material. 

Balance  in  Equipment. — One  of  the  most  important  problems 
in  power-shovel  mining  equipment  is  the  selection  of  the  proper 
number  of  machines  of  each  kind  to  most  efficiently  balance  all 
operations.  Such  a  balancing  of  equipment  must  be  determined 
for  each  property.  The  governing  factor  is  the  desired  output. 
Theoretically,  if  the  ore  production  is  to  be  a  given  amount  and 
the  ratio  of  overburden  to  ore  is  known,  the  amount  of  yardage 
to  be  excavated  per  day  can  be  stated.  Then  by  estimating  the 
capacity  of  the  type  of  shovel  selected  when  working  under  the 
local  conditions,  the  number  of  shovels  required  can  be  deter- 
mined. The  shovel  will  then  be  considered  as  the  governing 
unit  of  equipment  and  the  endeavor  will  be  made  to  reduce  to  a 
minimum  delays  to  its  operation.  With  this  in  mind,  the  proper 
number  of  locomotives,  cars  and  drills  will  be  estimated.  Most 
of  these  conclusions  will  require  considerable  experimental  work 
because  there  are  so  many  factors  which  enter  in  to  each  individual 
problem  that  they  cannot  be  expressed  by  a  mathematical 


108  STEAM  SHOVEL  MINING 

formula.  Some  10  to  20  per  cent,  additional  equipment  should 
be  added  for  spares. 

At  one  important  efficiently  operated  property,  having  eight 
95-ton  steam  shovels,  it  was  found  that  the  greatest  efficiency 
resulted  using  five  shovels,  moving  about  1200  cu.  yd.  solid 
per  shift,  and  thirteen  65-ton  locomotives.  Of  the  thirteen 
locomotives,  eleven  were  kept  serving  the  shovels,  one  was  doing 
general  switching  and  other  duty,  and  one  was  up  for  repairs. 
The  capacity  of  the  locomotives  depended  on  the  grades  from 
and  to  the  shovels  and  the  length  and  grade  of  track  to  the  dumps. 
About  seventy-five  20  cu.  yd.  dumps  cars  could  have  been  used 
to  advantage  but  there  were  only  about  sixty;  of  these  about 
fifty-five  were  kept  in  service  and  the  other  five  were  on  the  rip 
track  for  repairs.  Perhaps  an  average  of  1J^  shovels  were 
kept  working  in  ore  and  consequently  loading  directly  into  ore 
cars,  while  an  average  of  3J^  shovels  were  working  in  over- 
burden requiring  the  service  of  the  20-cu.  yd.,  dump  cars.  There 
were  periods  when  an  increase  in  ore  output  was  called  for  so 
that  it  became  necessary  to  put  more  shovels  in  service  at  the 
expense  of  efficiency.  At  other  times  it  became  necessary  to 
remove  overburden  at  a  number  of  places  simultaneously  in 
order  to  uncover  sufficient  ore  for  the  normal  daily  requirements, 
and  to  ship  material  for  treatment  that  would  approximate 
the  character  of  " average  ore."  This  required  spotting  shovels 
at  a  larger  number  of  paces  which  increased  the  number  in  serv- 
ice and  decreased  the  efficiency.  Under  ordinary  stripping 
conditions  it  was  found  that  two  locomotives  should  satisfactorily 
serve  one  shovel,  each  making  7  or  8  round  trips  per  9  hour 
shift,  and  that  7  or  8  overburden  cars  were  required  for  each 
locomotive. 

It  was  found  that  about  eight  No.  5  Keystone  drills,  drilling 
an  average  of  50  ft.  of  6  in.  hole  per  9  hour  shift,  were  required 
to  keep  ore  and  overburden  broken  ahead  for  7  shovels. 

At  another  property,  working  in  rather  harder  material,  there 
were  eleven  100-ton  shovels;  twenty-one  50-ton  locomotives; 
seventy-five  dump  cars,  of  which  about  fifty  were  small  12  cu.  yd. 
cars,  and  twenty-five  were  of  20  cu.  yd.  capacity;  and  ten  churn 
drills  on  blast-hole  drilling.  Some  supplementary  drilling  was 
done  by  air  drills.  There  was  a  shortage  of  at  least  thirty  20  cu. 
yd.  cars.  Here  also  the  shovels  working  in  ore  loaded  directly 
into  ore  cars. 


MECHANICAL  EQUIPMENT  109 

A  third  property  operated  with  twenty  95-ton  shovels;  thirty 
various  sized  locomotives,  and  about  250  dump  cars  averaging 
about  12  cu.  yd.  capacity.  The  ore  was  loaded  directly  into  ore 
cars. 

A  Mesabi  stripping  operation  called  for  3  type  91  (120  tons) 
Marion  steam-shovels;  10  standard  locomotives  with  19  in.  X 
26  in.  steam  cylinders;  110  20-cu.  yd.  K.  &  J.  automatic  air- 
dump  cars;  1  wrecking  crane;  1  dump  plow;  and  2  flat  cars. 
Here  no  drilling  and  blasting  was  required  except  for  breaking 
boulders. 

All  of  'the  above  mentioned  equipment  is  of  standard  gauge 
and  uses  steam  power. 

There  are  openpit  operations,  such  as  those  in  the  Kansas 
coal-fields,  where  the  overburden  need  neither  be  blasted  nor 
transported  beyond  the  reach  of  the  shovels.  In  such  cases  the 
ratio  of  stripping  equipment  to  coal  removal  equipment  is  more 
simple. 

On  some  works,  where  large  revolving  300-ton  shovels  are 
used,  the  best  possible  train  service  to  shovels  is  further  empha 
sized.  On  an  important  canal  job  in  Ontario  four  trains  were 
provided  for  each  300-ton  electric  shovel  Each  of  these  trains 
consisted  of  one  50-ton  electric  locomotive  and  ten  20-cu.  yd. 
automatic  air-dump  cars.  The  haul  from  shovel  to  dump  was 
from  2  to  2J^  miles  on  1  per  cent,  adverse  grade.  As  many  as 
290  of  the  20  cu.  yd.  cars,  (actually  carrying  about  17  cu.  yd. 
water  measure)  were  loaded  per  10  hours.  The  shovel  record 
was  about  8500  solid  cubic  yards  of  earth  excavated  in  two  shifts. 
This  material  required  no  blasting.  The  canal  section  in  earth 
ran  about  160  ft.  wide  at  the  top,  50  ft.  wide  at  bottom  and  45 
ft.  deep. 

Life  of  Equipment. — The  life  of  equipment  depends  not  only 
on  the  class  of  work  upon  which  it  is  put  but  on  the  care  with 
which  it  is  handled  and  the  thoroughness  and  promptness  of 
making  repairs. 

On  the  iron  ranges,  the  useful  life  of  steam  shovels  should 
average  from  12  to  15  years;  their  annual  shop  bill  for  repairs 
will  run  from  $3,500  to  $6,000.  In  winter,  working  on  over- 
burden, the  general  repairs  to  shovels  has  run  as  high  as  10  cents 
per  cu.  yd.  of  material  moved.  Obviously  a  properly  designed  new 
shovel,  or  one  just  thoroughly  shop-overhauled,  should  show  less 
repair  cost  than  a  shovel  old  in  the  service. 


110  STEAM  SHOVEL  MINING 

On  moving  25,000,000  cu.  yd.  of  material  at  Panama,  the 
average  repair  cost  was  2.815  cents  per  cu.  yd.  with  a  range  of 
from  1.35  cents  to  3.37  cents. 

Some  allow  the  useful  life  of  a  shovel  to  be  20  years,  assume 
that  the  first  cost  of  a  shovel  will  be  on  a  basis  of  $200  per  ton 
and  the  scrap  value  will  be  $10.  per  ton.  This  would  show  a 
straight  line  depreciation  of  4.75  per  cent,  per  annum  on  the 
first  cost  of  the  shovel.  Shovels  have  been  rented  at  from  $250 
to  $400  per  month,  depending  on  their  size  and  condition. 

Coarse  Crusher  Plants. — In  more  recent  practice  it  has  been 
found  that  the  reduction  in  site  of  matzrial  to  be  loaded  by 
shovels  has  been  very  desirable  before  shipping  to  the  treatment 
plants.  In  some  cases  it  has  fallen  to  the  lot  of  the  mine  to  effect 
this  reduction  and  in  such  cases  the  mine  has  been  charged  with 
the  installation  and  operation  of  a  coarse  crusher  plant.  Not- 
able illustratons  of  this  are  to  be  found  at  the  mines  of  the  Chino 
Copper  Company  and  Biwabik  Iron  mine.  These  will  be  briefly 
described  and  serve  to  illustrate  the  subject. 

Chino  Coarse  Crusher  Plant. — The  Chino  Copper  Company 
selected  a  good  site  for  a  coarse  crusher  plant  at  a  point  about 
one  half  mile  west  of  the  principal  orebodies.  It  was  designed 
to  handle  very  coarse  pieces  of  ore  encountered  in  shovel  opera- 
tions in  certain  portions  of  the  mine.  It  has  been  found  that 
breaking  these  fragments  by  the  usual  means  of  dobying  or 
drilling  and  breaking  by  hand  involved  not  only  serious  delay 
to  the  shovels  but  also  considerable  increase  in  mining  cost. 
On  the  other  hand,  if  they  were  loaded  without  breaking  and 
sent  to  the  mill,  the  difficulty  and  expense  of  handling  them 
through  the  ore  bins  and  coarse  crusher  plant  at  that  point  was 
even  greater.  The  machinery  selected  for  the  mine  crusher 
was  intended  to  be  of  sufficient  capacity  to  receive  the  largest 
pieces  of  rock  that  could  be  loaded  by  a  steam  shovel  and  to 
crush  it  to  a  size  convenient  to  handle  at  the  mill.  It  was  in- 
tended to  put  only  such  tonnage  through  this  crusher  as  came 
from  the  harder  areas  of  the  orebodies  and  which  in  the  ordinary 
process  of  blasting  broke  too  coarse  to  go  direct  to  the  coarse 
orebins  and  crushing  department  at  the  concentrator.  By 
removing  this  cause  of  delay  at  the  shovels  in  ore,  it  was  ex- 
pected to  increase  the  shovel  efficiency  and  decrease  the  cost  of 
mining  and  shipping.  The  construction  of  this  crusher  was 
started  in  the  latter  part  of  1913  and  completed  and  put  in 


MECHANICAL  EQUIPMENT  111 

operation  in  August  1914.  It  immediately  began  to  give  the 
expected  results  in  reducing  mining  costs  and  in  substantially 
decreasing  the  unloading  force  at  the  mill.  The  management 
stated  that  mining  costs  for  the  year  1915  had  been  reduced  by 
at>out  2.66  cents  per  ton  due  to  the  operation  of  this  crusher 
plant. 

A  description  of  this  crusher  plant  follows : 

The  oversize  ore  is  hauled  from  the  shovels  to  the  crusher  in 
standard  dump  cars  which  are  dumped  on  a  grizzly  about  50 
feet  wide,  accomodating  two  cars,  and  sloping  at  an  angle  of 
45°  for  a  length  of  30  feet.  The  grizzly  bars  are  8-in.  I-beams 
set  8  in.  apart  and  covered  with  manganese-steel  plates  to  protect 
them.  The  undersize  passes  through  the  grizzly  and  into  a 
bin  from  which  it  is  fed  onto  a  48-in.  pan  conveyor  operated 
by  a  100  h.p.  motor  and  located  at  a  point  below  the  crusher, 
and  on  this  conveyor  it  joins  the  crushed  ore  which  has  passed 
through  the  crusher.  The  oversize  material  passes  over  the 
grizzly,  its  fall  is  broken  by  a  buffer  and  it  is  fed  into  the  mouth 
of  a  Power  &  Mining  Machinery  Co.  jaw  crusher  48  in.  X  60  in. 
in  size.  About  200  h.p.  is  required  to  drive  this  crusher.  Its 
discharge  opening  is  set  to  about  8  in.  and  the  crushed  material 
is  fed  onto  the  pan  conveyor.  This  conveyor  elevates  the 
material  into  a  bin  from  which  it  is  loaded  into  railroad  cars. 
The  feed  to  the  conveyor  is  irregular^coming  in  rushes  as  the  cars 
are  dumped,  and  for  this  reason  the  speed  of  travel  of  the  con- 
veryor  is  relatively  high,  viz.  45  feet  per  minute.  The  bins  are 
of  steel  and  have  about  500  tons  capacity,  being  about  15  feet 
wide,  40  feet  long  and  20  feet  deep.  The  ore  is  drawn  off  from 
each  side  of  the  bin,  by  aproned  arc  gates,  into  cars  which  may 
be  assembled  by  gravity  on  tracks  laid  on  1J£  per  cent,  gradient. 
When  the  ore  is  moist  or  clayey  it  funnels  badly  and  must 
be  assisted  out  of  the  bin  if  the  bin  is  to  be  emptied.  The  cost 
of  this  plant  has  been  about  $150,000.  The  complete  cost  of 
crushing,  from  the  dumping  of  the  cars  to  the  loading  from  the 
bin,  exclusive  of  administration  expense,  runs  from  2  to  3  cents 
per  ton,  being  about  two-thirds  for  labor  and  one-third  for  sup- 
plies, etc.  About  14  men  are  employed  on  all  work  in  connection 
with  the  plant.  Power  costs  about  $50.00  per  h.p.  year.  About 
3000  tons  of  coarse  material  are  treated  on  the  day  shift  only. 
This  is  roughly  one-third  of  the  total  production.  The  improve- 
ment in  results  at  the  mill  crusher  and  in  elimination  of  delays 


112  STEAM  SHOVEL  MINING 

at  the  shovels  has  been  marked.  The  cost  of  unloading  coarse 
ore  at  the  mill  has  been  considerably  reduced.  With  the  ir- 
regular feed  mentioned  the  capacity  of  this  plant,  actually 
crushing  only  about  one-half  of  the  material  dumped  on  the 
grizzly,  is  somewhat  in  excess  of  3000  tons  per  shift.  It  seldom 
has  to  handle  pieces  larger  than  2  feet  in  diameter  but  sticky 
wet  fines  when  mixed  with  the  coarse  material  tend  to  clog  up 
the  chutes. 

The  Swedish  magnetite  mines  at  Kiiruna  also  have  a  jaw  type 
of  breaker,  built  by  the  Power  &  Mining  Machinery  Company, 
with  a  rated  capacity  of  500  tons  per  hour  and  weighing  ap- 
proximately 150  tons. 

The  Biwabik  Mine  Crusher  Plant. — This  property,  on  the 
Mesabi  range,  was  the  first  to  introduce  the  steam  shovel, 
systematic  sampling  and  mixing  of  ore  and  preliminary  crushing 
of  the  ore  at  the  mine. 

A  No.  24  Allis-Chalmers  breaker,  with  48  in.  receiving  open- 
ing, capable  of  handling  the  largest  and  heaviest  pieces  of  ore 
that  a  3-cu.  yd.  shovel  can  take,  was  installed.  This  is  driven 
by  a  200-h.p.  belted  induction  motor.  In  designing  the  plant, 
the  engineers  considered  the  merits  of  jaw  and  gyratory  crushers, 
and  chose  the  latter  because  it  was  believed  that  the  crushing 
would  be  more  continuous;  less  shock  requiring  cheaper  founda- 
tions; less  liability  to  breakage;  and  that  the  large  circular 
receiving  opening  would  permit  the  discharge  of  an  entire  carload 
into  the  breaker  without  having  chutes  leading  to  it  for  feeders. 
The  results  have  been  very  satisfactory,  and  to  put  through  1000 
tons  per  hour,  is  usually  a  question  of  getting  the  cars  to  the 
dumping  platform  fast  enough.  The  ore  is  dumped  over  a 
grizzly  14  ft.  wide,  with  bars  spaced  2  in.  apart;  the  undersize 
falls  through  and  into  a  spout  inclined  at  50°  leading  to  one  of  the 
shipping  bins.  The  receiving  opening  of  the  crusher  is  48  in. 
clear  between  crushing  surfaces  and  is  125  in.  long.  The  crushed 
product  passes  through  a  revolving  screen  with  2-in.  holes. 
It  is  6  ft.  dia.  X  13  ft.  long,  inclined  1%  in.  per  foot,  and  driven, 
by  a  30-h.p.back-geared  motor.  The  undersize  from  this  2  in 
screen  joins  the  undersize  from  the  grizzly.  The  oversize 
from  the  screen,  ranging  from  2  in.  to  5  in.  falls  into  a  separate 
shipping  bin.  Good  provision  has  been  made  for  all  lubrication. 
The  electric  power  for  the  plant  is  steam  generated  on  the  spot. 
As  some  of  the  chunks  of  ore  handled  by  the  shovels  weigh  as 


MECHANICAL  EQUIPMENT  113 

much  as  6  or  8  tons  it  will  be  seen  that  the  crusher  was  built 
for  heavy  duty. 

The  approximate  cost  of  the  plant,  with  all  machinery  in- 
stalled and  including  electric  equipment  was  stated  to  be  less  than 
$75,000.  The  average  cost  of  crushing  is  about  1.5  cents  per  ton. 
The  operating  crew  consists  of  10  men,  viz.  a  foreman  who  looks 
after  the  electrical  equipment,  5  dump  men  who  unload  cars  and 
tend  to  the  feeding  and  4  brakemen  who  look  after  the  discharge 
and  car  loading.  In  1914  this  company  shipped  255,255,  tons  of 
ore,  and  this  installation  resulted  in  a  minimum  of  reblasting 
in  the  pit.  The  ores  are  as  a  rule  quite  hard,  requiring  machine 
drills  in  blasting. 

Ore  Dryers. — Another  type  of  equipment  which  an  open-pit 
mine  is  sometimes  called  upon  to  install  and  operate  is  an  ore 
dryer.  It  would  seem  that  it  had  little  connection  with  open- 
pit  mining,  but  a  brief  description  will  show  its  mission. 

The  function  of  a  dryer  is  to  drive  off  free  moisture;  it  does 
so  by  the  application  of  heat  and  is  thus  distinct  from  a  de- 
hydrator,  which  extracts  moisture  by  mechanical  means,  and 
from  a  calciner,  which  drives  off  combined  moisture  and  other 
volatiles  by  roasting  at  high  temperature.  Many  classes  of 
materials  are  successfully  dried  by  this  means,  and  among  these 
are  some  of  the  iron  ores  of  the  Mesabi. 

Many  ores  are  now  being  dried  to  enable  them  to  be  concen- 
trated by  electrostatic  separation  and  other  methods;  some  are 
dried  because  it  is  less  expensive  to  evaporate  the  water  from  the 
ore  than  to  pay  the  freight  charges  for  its  transportation;  often 
there  is  a  considerable  saving  in  handling  the  dried  product,  if 
when  wet  it  is  liable  to  freeze  in  the  cars  or  stock  piles,  or  seriously 
interfere  in  crusher  feeding  operations  or  furnace  charging.  In 
the  case'  of  iron  ores,  there  is  not  only  a  saving  in  freight,  but  a 
higher  premium  is  obtained,  because  elimination  of  the  moisture 
naturally  brings  up  the  iron  content  in  the  product  as  sampled. 

Thus  an  ore  containing  20  per  cent,  moisture  and  48  per  cent. 
Fe.  in  its  natural  state  may  be  raised  to  56.6  per  cent.  Fe.  when 
dried  to  6  per  cent,  moisture.  Furthermore,  the  dried  product 
is  often  better  to  treat  in  the  furnaces,  as  fuel  and  linings  can 
be  saved  and  the  capacity  can  be  increased. 

Without  going  into  details,  actual  installations  of  driers  have 
been  shown  to  utilize  from  75  to  80  per  cent,  of  the  thermal  value 
of  the  fuel  A  consumed.  The  Ruggles-Coles  dryers  are  double 


114         STEAM  SHOVEL  MINING 

shelled  revolving  cylindrical  furnaces  built  in  different  sizes, 
from  80  in.  to  104  in.  in  diameter  and  from  45  ft.  to  75  ft.  long. 
The  moisture  is  exhausted  by  means  of  an  exhaust  fan. 

In  practical  drying  operations  at  a  particular  property  it  has 
been  found,  in  reducing  the  moisture  content  from  18  per  cent. 
to  8  per  cent.,  using  as  fuel  Pittsburg  bituminous  dock  screen- 
ings costing  $3.00  per  ton  and  including  3  to  5  cents  per  ton 
as  the  cost  of  transporting  the  wet  ore  to  the  bins  before  treat- 
ment begins,  that  the  cost  has  varied  from  13  to  25  cents  per 
ton  with  18  cents  as  an  average. 

Installations  of  this  type  may  be  seen  on  the  Mesabi  at  the 
Whiteside  mine  of  the  Shenango  Furnace  Company,  near  Buhl 
and  at  the  Brunt  mines  of  the  Pittsburg  Iron  Company  near 
Virginia,  Minn. 

In  conclusion  it  may  be  said  that  there  is  a  legitimate  field  for 
the  ore  dryer,  and,  under  proper  conditions,  its  use  will  result 
•in  a  good  saving  to  the  mine  operator. 


\ 


CHAPTER  III 


METHODS  OF  ATTACK 
GENERAL  PROBLEMS 

Shovel  excavation  may  be  classified  under  four  general  prob- 
lems, viz.,  Bench  work,  Thorough-cut,  Casting-over  and  Course- 
stacking.  A  problem  may  be  made  up  of  a  combination  of 
these.  Their  difference  lies  principally  in  the  method  of  dis- 


Bench  A 


Crest 


CL.of  Shovel 


CL.of  Shovel       CL.of  Ldadinq 
{         Track 


Outline  of 
Bench  being 
Cut  by  Casting - 
Over. 

( 

CastinqOver 

Replacement  Work       _  i 

A,B,&C  are  Illustrated  with  R.  R  Type  Shovels,  while  D  is  Illustrahd  with  Large  Revolving  Type  Shovel. 
All  Methods  might  bt  done  with  either  Type  of  Shovel 
Not  *o  Scale 

FIG.  18. — Four  problems  of  excavation. 

posing  of  the  spoil.     Fig.   18  A-B-C-D,  illustrates  these  four 
general  problems. 

Bench  Work. — This  method  of  attack  is  widely  used  in  mining 
large  iron  and  copper  deposits.  It  consists  in  digging  from 
bank  or  face  on  one  side  or  directly  ahead  of  the  shovel  course, 
and  loading  the  spoil  into  cars  on  a  passing  track  on  the  same 
level  and  the  opposite  side  of  the  shovel.  In  Fig.  18-A,  bank 
B  is  being  attacked  at  the  expense  of  bench  A,  but  at  the  same 

115 


116  STEAM  SHOVEL  MINING 

time  bench  B  is  being  widened.  Thus  if  the  upper  benches  are 
to  be  maintained  their  banks  must  likewise  be  worked  back  to 
keep  pace  with  the  lower  encroachment.  With  some  deposits 
it  is  possible  to  do  the  stipping.in  one  bench,  but  where  the 
thickness  is  great  it  is  necessary  to  work  it  off  in  a  series  of 
benches  or  terraces. 

Height  of  Banks. — One  of  the  first  questions  to  decide  in  bench 
work  is  what  shall  be  the  best  average  height  to  carry  the  banks. 
The  principal  factors  in  determining  this  are,  the  total  thickness 
,  of  the  deposit,  its  physical  character,  climatic  conditions,  the 
method  of  blasting  and  degree  of  fragmentation  desired,  and  the 
specifications  of  the  shovels  to  be  used.  In  case  ore  and  waste 
are  both  to  be  mined,  careful  consideration  in  planning  banks 
must  be  given  to  the  line  of  demarkation  between  the  two,  other- 
wise a  mixture  will  result.  If  this  line  is  very  irregular  the 
problem  becomes  difficult  for  that  horizon,  and  considerable 
variation  in  bank  height  may  become  desirable  in  order  to  keep 
both  products  as  clean  as  possible.  Sorting  ore  from  waste 
with  a  shovel  from  a  bank  can  to  a  certain  extent  be  done,  but  it 
greatly  reduces  the  efficiency  of  the  shovel,  and  there-  is  sure  to 
be  some  admixture  of  the  two  materials. 

Several  of  the  factors  involved  will  be  more  or  less  interde- 
pendent. Careful  consideration  must  be  given  to  the  safety 
of  the  crews  and  equipment  as  well  as  to  the  economics  of  the 
problem.  Banks  in  some  ground  stand  well  for  great  heights 
while  in  other  ground  they  crumble  and  slough  off,  assuming 
rather  flat  slopes.  The  higher  the  bank  the  flatter  will  be  the 
safe  slope.  In  working  very  high  banks  there  is  always  more  or 
less  danger  to  men  and  equipment  working  below  from  pieces 
sloughing  off.  In  blasting  them  greater  burden  is  thrown  on 
the  toe,  so  that  shovels  and  tracks  are  sometimes  buried. 

The  following  remarks  may  be  taken  to  apply  to  both  over- 
burden and  ore  where  both  classes  of  material  are  to  be  mined. 

A  flat-lying  deposit  having  a  fairly  regular  contour  and  a 
moderate  but  fairly  even  thickness,  may  be  mined  out  in  one 
bench.  Such  deposits  are,  however,  rare,  and  it  will  generally 
be  necessary  to  divide  the  work  into  the  fewest  number  of  benches 
that  will  fit  the  characteristics  of  the  deposit  and  the  methods 
to  be  adopted  in  working  it. 

If  the  material  is  of  a  soft,  rotten  or  highly  shattered  character 
it  will  generally  break  quite  well  when  blasted  by  any  method 


METHODS  OF  ATTACK  117 

that  will  serve  to  shake  it  up.  If,  however,  it  is  hard  and  not 
much  broken  by  natural  fracture  or  cleavage,  high  banks,  blasted 
in  one  stage,  are  almost  sure  to  break  with  a  large  proportion  of 
"  oversize. "  It  is  generally  found  simpler  or  more  convenient 
to  blast  the  banks  in  one  stage  than  in  several,  as  will  be  further 
explained  under  "Drilling  and  Blasting,"  Chap.  IV.  It  is 
usually  very  undesirable  to  have  banks  break  with  a  large  amount 
of  oversize.  This  material  causes  delays  in  loading,  and  may 
later  be  found  very  annoying  at  the  reduction  works.  Large 
loosened  masses  may  be  left  hanging  in  the  banks,  and  must  be 
carefully  guarded  against  lest  they  endanger  crews  and  equip- 
ment. -  For  these  reasons,  in  the  case  of  hard  tight  ground,  it  is 
desirable  to  keep  the  height  of  banks  low  enough  to  insure 
reasonably  good  fragmentation  and  safety.  Even  under  special 
conditions,  where  hard  large  material  is  desired,  it  will  generally 
be  found  better  to  work  banks  of  moderate  height  both  on 
account  of  safety  and  general  working  control.  It  may  be  noted 
that  hard  rock  is  often  cut  by  prominent  slips  and  faults,  and 
where  these  occur  they  should  be  given  proper  attention  in 
planning  the  work. 

Climatic  conditions  may  have  an  important  bearing  on  the 
best  height  to  which  the  banks  may  be  carried.  For  example, 
material  that  is  soft,  decomposed  or  highly  shattered  may  be 
found  to  work  down  very  well  from  banks  of  great  height  in  dry 
or  arid  climates.  The  same  material,  when  wet,  may  have  a 
decided  tendency  to  run  or  come  down  in  rushes,  thus  causing 
loss  of  control  of  the  banks.  Examples  of  this  class  of  material 
have  been  seen  where  the  banks  stood  perfectly  well  during  the 
dry  summer  months,  but  when  saturated  with  rain  or  melting 
snows  and  frost,  they  would  so  slush  down  as  to  cover  the  benches 
and  tracks  and  thus  give  much  trouble.  Decomposed  porphyry 
and  talcose  material  is  especially  apt  to  act  in  this  way.  Some 
examples  have  been  noted  in  plastic  ground  where,  although 
the  banks  stood  up  fairly  well,  the  bench  bottoms  were  badly 
squeezed  up  or  out  by  the  superincumbent  weight  of  the  banks. 
In  working  such  material  under  wet  climatic  conditions,  it  is 
better  to  keep  the  height  of  banks  moderately  low,  and  to  allow 
them  to  stand  at  rather  a  flat  angle  of  repose  if  the  benches  are 
expected  to  be  kept  open  for  sometime.  In  regions  of  heavy 
snowfall  and  wind,  it  is  found  that  pit  banks  offer  good  snow- 
breaks;  hence  the  benches  are  often  heaped  with  snow-drifts,  and 


: 


118  STEAM  SHOVEL  MINING 

they  must  be  cleared  out  before  traffic  can  be  resumed.  With 
high  banks  the  drifts  may  at  times  come  up  to  the  tops  and  com- 
pletely cover  stretches  of  the  benches.  Thorough  cuts  are  even 
more  apt  to  become  snow  filled,  and  are  more  difficult  to  clean 
out. 

The  relationship  between  height  of  bank  and  shovel  dimen- 
sions was  pointed  out  in  Chap.  II,  p.  46. 

Using  shovels  of  the  railroad  type,  it  has  been  found  in  prac- 
tice that  about  the  most  satisfactory  and  economical  bank  is 
one  having  a  height  equal  to  the  horizontal  distance  measured 
from  the  center-line  of  the  loading  track  to  a  point  on  the  bank 
six  feet  above  the  rail.  Reference  to  Chapter  I,  table  2,  shows 
this  to  be  A  +  E  —  2,  or  for  a  type  100C  shovel,  this  would  be 
29  ft.  +  33  ft.  --  2  ft.  =  60  ft.  Using  shovels  of  the  largest 
revolving  type — which  might  be  done  on  very  wide  benches — it 
is  not  considered  advisable  to  carry  banks  over  50  feet  high  in 
tight  unshot  material,  or,  in  other  words,  much  above  the  reach 
of  the  dipper,  because  if  so,  the  bank  would  tend  to  be  undercut. 
If,  however,  these  large  shovels  were  to  be  placed  on  loading  from 
soft  banks,  or  banks  well  blasted,  where  the  material  would 
naturally  tend  to  feed  down  to  the  shovel,  the  height  might  be 
much  increased,  as  there  would  be  no  tendency  to  undercut. 
It  might  be  necessary,  however,  to  keep  " trimming"  them  to 
even,  slope  so  that  the  material  would  not  come  down  in  heavy 
rushes. 

In  theory,  on  a  multiple  bench  job,  the  higher  the  banks,  i.e., 
the  greater  the  vertical  distance  that  can  be  allowed  between 
benches,  the  more  economical  will  become  the  removal  of  over- 
burden, and  the  more  efficient  the  shovel  operation.  There  will 
be  a  smaller  total  yardage  of  overburden  to  remove  because  less 
horizontal  area  will  Jiave  to  be  exposed  to  allow  for  the  area  of  the 
benches  eliminated.  In  other  words,  a  steeper  average  slope  from 
crest  to  toe  of  stripping  can  be  realized.  With  deep  or  steeply 
dipping  deposits  the  volume  of  slope  yardage  may  become  for- 
midable. Reference  to  Fig.  2,  in  Chapter  I.  will  illustrate 
this.  Also  the  shovel  operation  will  be  more  efficient  because 
there  will  be  less  time  consumed  in  moving  the  shovel  ahead, 
and  it  can  work  in  one  spot,  so  that  its  loading  time  may  be 
correspondingly  increased. 

In  practise,  however,  the  height  of  banks  should  be  kept  down 
to  reasonably  safe  working  conditions.  It  may  furthermore  be 


METHODS  OF  ATTACK  119 

desirable  to  provide  additional  benches  SQ  that  there  will  be 
plenty  of  working  faces,  or  separate  faces  as  natural  divisions 
between  different  classes  of  ore  or  between  ore  and  waste.  Con- 
sideration of  trackage  arrangements  may  also  require  a  reduction 
in  bank  heights  because  in  running  from  bench  to  bench  the 
gradients  must  be  kept  reasonable.  The  total  rise  possible  is 
the  product  of  the  grade  by  the  allowable  length  of  track.  The 
problem  is  thus  a  compromise  between  theoretical  economy 
and  practical  conditions,  but  there  are  reasonable  limits  in  both 
cases.  \ 

Benches  less  than  12  feet  high  are  not  economical,  from  the 
standpoint  of  shovel  operation,  because  there  is  too  much  time 
spent  in  moving  ahead;  and  benches  over  75  feet  high  are  liable 
to  be  difficult  to  control.  Most  work  can  be  carried  on  some- 
where within  this  range. 

In  the  anthracite  coal  regions  of  Pennsylvania,  rock  cuts  are 
usually  carried  from  22  to  25  feet  high,  though  more  recently 
these  have  been  reduced  to  12  or  15  feet,  depending  somewhat  on 
the  nature  and  hardness  of  the  rock.  The  lower  heights  are 
recommended  for  very  hard  rock  because  it  has  been  found  that 
they  give  better  results  in  blasting.  The  higher  banks,  and  more 
especially  their  upper  portions  do  not  always  break  well  with  the 
system  of  blasting  employed,  and  hence  the  material  is  more 
difficult  to  load.  A  saving  of  as  much  as  25  per  cent,  in  the  cost 
per  cu.  yd.  of  stripping  has  been  claimed  for  the  lower  banks. 

On  the  Mesabi,  benches  of  from  25  to  30  feet  in  height  are 
preferred. 

In  the  open-pit  copper  mines,  they  are  generally  carried  45  to 
60  feet  high.  The  Utah  Copper  Company  has  even  worked 
successfully  one  particular  bank  of  ore  240  feet  high.  This  was 
not  done  from  choice  but  because  of  production  requirements  and 
particular  physical  conditions.  Banks  of  this  height  are  very 
likely  to  over  shoot  the  loading  tracks,  bury  the  shovel,  and  give 
a  large  amount  of  oversize  material  which  must  bejeshot.  They 
are  not  under  the  same  control  as  lower  ones  and  must  be  handled 
with  particular  care  and  kept  well  trimmed.  The  method  of 
shooting  must  also  be  different. 

The  slope  or  angle  of  repose  of  a  bank  depends  on  the  nature  of 
the  material,  its  height,  and  if  blasted,  how  it  was  blasted. 
This  angle  of  repose  is  also  called  the  slope  ratio.  In  this  case1 
the  vertical  height  is  taken  as  unity  and  stated  last;  thus  a  slope 


120  STEAM  SHOVEL  MINING 

of  2  to  1  ratio  would  indicate  a  base  of  2  and  vertical  height  of  1, 
and  a  1  to  1  slope  would  be  at  45°. 

Width  of  Benches. — The  width  of  benches  is  subject  to  less 
variation  than  the  vertical  distance  between  them.  They  should 
be  wide  enough  to  carry  the  loading  track  and  provide  for  the 
shovel  course.  The  distance  between  these  track  centre  lines, 
or  the  dumping  radii,  for  the  various  types  and  sizes  of  shovels 
is  given  in  the  tables  in  Chapter  I  and  by  Figs.  12  and  13,  Chapter 
II.  If  the  ground  requires  blasting  the  width  should  be  increased 
so  that  the  benches  may  be  drilled  and  the  banks  shot  without 
danger  of  caving-in  the  loading  track  above  or  covering  up  the 
loading  track  on  the  bench  below.  Ordinarily  broken  material 
will  repose  at  a  slope  of  about  1J/2  to  1  but  rock. blasting  usually 
kicks  it  out  flatter,  or  say  to  2  to  1. 

If  the  banks  are  shot  well  ahead  of  shovel  operations  it  will  be 
possible  to  do  the  drilling  and  shooting  more  methodically. 
The  shovels  may  also  work  along  with  less  interruption  or  fear 
of  damage  due  to  blasting.  It  may  be  necessary  to  widen  some 
benches  in  places  to  allow  for  switches  or  passing  tracks.  During 
operation  they  will  seldom  be  less  than  50  feet  wide,  but  where 
advance  blasting  or  additional  trackage  is  required  may  be 
considerably  wider. 

Pit  Slopes. — The  height  and  width  of  a  series  of  benches  will 
give  the  general  pit  slope  and(  as  was  pointed  out/  it  is  usually 
highly  desirable  to  conclude  the  work  leaving  'the  slopes  as 
steep  as  practicable  in  order  to  avoid  excess  overburden  re- 
moval. During  operations  it  may  be  found  best  to  carry  the 
pit  slopes  at  a  relatively  flat  angle,  but  as  the  work  draws  to  a 
close  it  will  often  be  found  possible  to  narrow  the  benches  and 
finally  to  lose  upper  benches  by  working  the  lower  ones  pro- 
gressively up  to  them.  For  example,  in  the  final  stages  of  opera- 
tion if  may  be  quite  possible  to  work  the  upper  two  50-foot 
banks  into  one  100-foot  bank,  then  do  the  same  thing  with  the 
next  two  lower  banks  and  so  on,  until  further  consolidation  is 
no  longer  safe  or  convenient.  Such  bank  consolidation  may  be 
broken  up  at  safe  intervals  by  simply  leaving  bench  remnants 
of  sufficient  width,  say  30  feet,  to  act  as  safety  berms.  These 
will  not  only  serve  to  stop  falling  material  which  may  become 
loosened,  but  may  still  be  used  as  inspection  ways. 

When  the  pit  plan  is  finally  laid  out  such  problems  should 
be  considered  with  the  aid  of  working  templates  cut  to  scale. 


METHODS  OF  ATTACK  121 

Upper  benches  should  not  be  carried  beyond  the  final  crest  of 
stripping  when  so  determined,  and  final  drilling  and  blasting  of 
banks  should  be  carefully  done  so  that  the  resulting  banks 
will  be  left  in  the  firmest  and  best  condition  to  stand  well  and 
safely  for  the  necessary  time  after  consolidation.  In  this  way 
it  may  be  possible  to  increase  the  final  pit  slopes  by  from  5°  to 
10°  or  more,  resulting  in  a  great  saving  of  yardage  removal  and 
disposition. 

Slides. — In  open-pit  work  slides  often  occur  in  wet  weather. 
To  guard  against  their  interference  with  operations  berms  of 
from  20  to  30  feet  may  be  left  at  suitable  intervals,  or  the  toes 
of  banks  may  be  cribbed  up  with  poles  or  ties  in  rip-rap  fashion, 
or  dry-walling  or  facing  may  be  resorted  to.  In  working  very 
high  banks  they  must  be  carefully  watched  and  trimmed  to 
guard  against  slides. 

Casting-over. — It  sometimes  ,  becomes  necessary  to  re- 
establish lost  benches  or  to  cut  up  a  high  bank.  In  so  doing 
there  may  not  be  room  for  a  loading  track  so  that  the  shovel  will 
simply  cut  its  course  discharging  the  dipper  over  the  side  of  the 
bank.  See  Fig.  18-C.  The  cast-over  material  may  have  to  be 
reloaded  from  the  bench  below.  Usually  after  making  one  cut  by 
casting-over,  a  loading  track  can  be  laid  and  bench-work 
continued. 

Thorough  Cut. — These  are  often  called  box  cuts.  In  com- 
mencing stripping  operations,  running  approaches  or  excavating 
ditches,  the  shovel  is  required  to  dig  below  grade  and  down 
grade.  The  dipper  is  discharged  into  cars  on  a  passing  track 
above  grade  or  the  material  may  be  dumped  on  the  bank  along 
the  shovel  course.  See  Fig.  18-B.  Reference  to  Table  2, 
Chapter  I.  shows  that  the  depth  of  cut  below  rail  for  standard 
equipment  is  from  4  to  6  feet  and  the  shovel  must  be  cribbed 
up  accordingly.  By  working  down  grade  progressively  this 
equipment  can  cut  thorough-cuts  to  maximum  depths  of  from 
8  to  16  feet.1  Having  finished  one  such  cut,  the  loading  track 
may  be  relaid  in  the  first  cut  and  a  second  one  started  along  side 
of  the  first.  In  this  way  a  cut  will  be  established  with  banks  on 
each  side  and  worked  until  sufficient  depth  and  length  is  reached 
to  begin  bench  work. 

1  For  special  work  on  canals  and  ditches  'special  equipment  set  on  rollers 
to  straddle  the  cut,  and  having  special  long  dipper  sticks  can  be  had,  but 
they  are  not  generally  used  in  mining  work. 


122  STEAM  SHOVEL  MINING 

Fig.  19  illustrates  a  method  of  dividing  a  100-foot  bank  into 
two  50-foot  banks  by  a  system  of  thorough-cuts.  Note  the 
difference  between  this  method  and  that  of  casting-over. 

First  Cut.—  The  location  and  method  of  the  first  shovel  cut 
will  depend  on  the  local  conditions.  On  some  jobs  of  irregular 


•    I&  Position  Loading 
Jrack 

~" 


**•""•»«.  io       y 

Loading  Track  -^         A   J^^       *   '     2&J?  CUT 

§  /       3^  CUT          \-7*-* .^   Loading  Track 

/SSN    4tb  Postf/on 

Sib 'Position       /     \!;oadin3jracL,     / 
Loading  ,     4^  CUT  /    S&CUT 

p  - "-  '     •          ..—-£5is Position 

Shovel  Track 


FIG.   19.  —  Dividing  bank,  thorough-cuts. 

surface  the  first  cut  is  run  through  the  pit  with  the  shovel  cutting 
on  grade  and  casting  the  spoil  to  the  sides.  In  this  grade  cut  a 
loading  track  is  then  laid  and  may  be  used  for  the  next  two  cuts, 
one  on  either  side.  If  the  ground  is  not  too  rough  the  first 
loading  track  may  be  laid  on  the  surface  but  care  must  be  given 

l&Loading 
\prigma1  Surface  A  ..-Track 


FIG.  20.  —  Thorough-cut  work. 


that  the  shovel  cut  does  not  tend  to  follow  the  undulations 
of  the  loading  track  resulting  in  an  irregular  profile.  Care  should 
also  be  given  to  the  loading  track  to  prevent  undue  wear  and 
derailment  of  equipment. 

On  some  jobs  the  large  300-ton  revolving  shovels  are  employed 


•, 


METHODS  OF  ATTACK  123 

on  thorough-cuts.  An  example  from  the  iron  ranges  is  given  on 
Fig.  20.1 

Here  the  loading  track  was  laid  on  the  surface  of  the  ground  at 
A;  the  shovel  reach  was  sufficient  to  keep  the  furthest  rail  clear 
of  spill.  The  small  divisions  numbered  1  to  10  indicate  the 
successive  cuts  which  would  have  been  required  had  a  100-ton 
standard  shovel  been  used  to  make  the  one  large  cut.  The  posi- 
tions of  the  loading  tracks  would  have  been  as  shown  by  the 
letters  A  to  H. 

In  some  instances  it  is  desirable  to  run  a  thorough-cut  by 
laying  the  loading  track  alongside  of  the  shovel  in  the  cut.  The 
depth  of  such  a  cut  is  not  then  limited  by  the  lift  of  the  dip- 
per. This  method,  however,  is  slow  because  only  one  waste  car 
can  be  spotted  at  a  time  at  the  shovel  and  as  soon  as  a  car  is 
loaded  it  must  be  switched  out  and  another  one  run  in.  The 
delays  to  shovel  operation  are  great  and  the  method  is  seldom 
employed.  It  is  sometimes  spoken  of  as  "butting  the  ut." 

Course -stacking. — In  this  system  the  haulage  of  earth  is 
entirely  eliminated  as  the  shovel  simply  excavates  from  one  side, 
swings  about,  and  discharges  the  dipper  on  the  opposite  side.  See 
Fig.  18-D.  The  first  cut  on  a  job  of  this  sort  will  be  a  thorough- 
cut  started  on  the  extreme  edge  of  the  area  to  be  stripped  and 
probably  at  a  place  where  the  overburden  is  shallowest.  The 
spoil  from  this  cut  will  be  deposited  on  ground  not  to  be  stripped. 
The  deposit  exposed  by  this  first  cut  will  then  be  removed,  the 
shovel  will  be  moved  over  for  the  next  cut,  which  will  be  a  bench 
cut,  and  wider  as  there  is  more  room  for  operation,  and  the  waste 
from  this  second  cut  will  be  deposited  and  stacked  on  the  area 
of  the  first  cut.  This  replacement  operation  will  be  repeated  for 
the  third  cut  and  so  on.  There  is  a  swell  of  about  25  per  cent,  in 
the  volume  of  the  broken  spoil  and  as  it  is  stacked  in  piles  the 
crests  of  these  piles  will  be  considerably  higher  than  the  original 
ground  unless  the  underlying  deposit  to  be  won  is  thick.  This 
method  is  largely  used  in  stripping  certain  coal  deposits.  Refer- 
ence to  Table  7,  Chapter  I,  shows  that  stripping  up  to  48  feet 
can  be  excavated  and  stacked  with  the  largest  of  the.  revolving 
shovels.  Fig.  21  shows  a  shovel  working  in  the  first  or  thorough- 
cut  and  Fig.  22  shows  a  later  cut  being  made  as  the  operation  is 
advanced.  The  material  shown  here  consists  of  flat  beds  of 

1  Steam-shovel  Mining  on  Mesabi  Range.  L.  D.  Davenport  E.  M.  J. 
March  2-30th,  1919. 


124  STEAM  SHOVEL  MINING 


FIG.  21. — Steam  shovel  working  in  thorough-cut. 


FIG.  22. — Steam  shovel  in  thorough-cut  after  operation  has  advanced. 


METHODS  OF  ATTACK  125 

shale  and  clay  seldom  requiring  any  blasting.     The  benches 
stand  almost  vertical. 

In  some  places  the  crests  and  troughs  of  the  stripping  rows  have 
been  balanced  by  hydraulicking.  This  leaves  the  land  less 
broken,  but  it  cannot  be  considered  of  much  value. 

PIT  LAYOUTS 

As  stated  in  Chapter  VI,  before  a  complete  coordinated  system 
of  working  an  open  pit  can  be  planned,  all  the  data,  covering  the 
shape,  size,  texture,  structure  and  relationship  of  the  deposit, 
to  the  enclosing  formation  should  be  known;  also  the  detailed 
conditions  for  waste  disposal,  such  as  location,  elevation  and 
capacity  of  dump  sites. 

Depending  on  these  conditions,  pits  maybe  planned  on  systems 
of  spirals,  switchbacks,  or  tees  and  wyes. 

Spirals. — Where  the  deposit  is  more  or  less  horizontal  and 
regular  in  outline  and  of  considerable  area,  the  spiral  system  is 
usually  adopted.  A  favorable  location  will  be  chosen  for  the 
approach  and  from  this,  spirals  will  usually  be  started  from  both 
sides.  Occasionally  separate  approaches  and  independent  spiral 
systems  will  be  planned  for  overburden  and  ore  removal.  The 
care  required  in  planning  curves  and  grades  will  be  mentioned 
in  Chapter  VI.  Some  examples  of  spiral  pit  systems  are  to  be 
seen  at  the  Shenango,  Buffalo,  Hull-Rust,  Mahoning  and  other 
mines  on  the  Mesabi  iron  range,  and  at  the  Nevada  Consolidated 
Copper  Company's  mine. 

Switchbacks. — Where  the  deposit  is  long  and  narrow,  irregu^ 
lar  in  outline,  or  inclined,  the  switchback  system  is  usually 
employed.  Inportant  examples  of  such  pits  may  be  seen  at  the 
Stevenson,  Fayal  and  other  mines  on -the  Mesabi,  at  the  Utah 
Copper,  *  and  at  the  Dehesa^and  Dionisio  mines  of  the  Rio 
Tinto  Company  in  Spain. 

The  Chino  Copper  Company's  ore  bodies  form  an  irregular 
annular  ring  and  are  worked  by  spirals  and  switchbacks. 

The  switchback  tail-tracks  waste  horizontal  distance  without 
gaining  ek nation.     Switchbacks  tend  to  slow  up  traffic  because 
'  of  having  to  stop  and  reverse  direction.     On  the  other  hand,  the 
problem  of  curvature  is  usually  simplified. 

Tees  and  Wyes. — Such  systems  are  often  used  in  mining  coal 
in  Kansas,  Ohio  and  Oklahoma.  Fig.  23  illustrates  a  typical 


126 


STEAM  SHOVEL  MINING 


example  of  this  system  as  employed  near  Pittsburg,  Kansas. 
Here  the  first  cut  is  made  at  right  angles  to  the  main  haulage- 
way;  the  spoil  is  cast  on  the  barren  edge  and  a  strip  of  coal  about 
50  ft.  wide  is  uncovered.  A  loading  track  is  then  branched  off 
from  the  main  haulage  way.  This  is  laid  on  the  far  edge  of  the 

Deep  End 


(To  1*S 

p. 

'ripped) 
»n 

-T* 

300-ton  Shovel 
L_                             B-.    / 

;     ~  :    7 

(Cuts  about  IS' wide 

<  at  Bottom.  Tees  may  be  any         -^ 

{Length  up  to  2000  Ft.  jj* 

Main  Haulaqe-wau                    \ 
outofPit%2"6auge- ? 


2V&  WASTE  ROW 
WASTE  ROW 


*  Low  Shallow  End 

J27D  Coal  Loader  Working 
at  A  in  Direction  of  Arrow 
300-ton  Revolving  Shovel, 
forking  ai-B  in  Direction 
of  Arrow. 


Spoil  Deposit 

45'HighW 

Mm 


Siding  for  3-ton'''  ftji 
Cars 

Tracks-4  Products: 
a  =  Mine  Run 

Mainline  R.R. 
50-ton  Cars  4-dt"     jf1 

b-  Lump 
c=  Nut 
a,       0'=  Slack 

Section    x-x' 

FIG.  23. — Tee  pit  layout;  Kansas. 

coal  strip.  The  coal  loader  is  then  put  to  work  at  one  end  of  the 
coal  strip  and  advances  toward  the  main  haulage-way  as  it 
removes  the  coal.  In  the  illustration,  the  1st  and  2nd  cuts  have 
been  stripped  and  over  two-thirds  of  the  3rd  is  finished.  All 
of  the  coal  has  also  been  removed  from  the  1st  and  2nd  cuts  and 


METHODS  OF  ATTACK  127 

a  start  is  being  made  on  the  3rd  strip.  The  3rd  cut  will  be  com- 
pletely stripped  and  the  stripping  shovel  moved  over  to  the  4th 
cut  before  much  of  the  coal  has  been  mined  from  the  3rd  cut. 

It  is  an  advantage  to  commence  operations  at  the  lower  side 
of  the  deposit  since  in  that  case  haulage  of  the  loads  will  have  a 
favorable  grade,  and  drainage  will  be  simpler. 

In  these  pits  the  overburden  averages  about  22  ft.  but  may  run 
up  to  44  ft.  The  coal  seams  are  quite  flat  and  average  about  36 
in.  but  may  run  up  to  42  in. 

Such  a  pit  could  be  worked  in  a  circular  form  but  not  so  ad- 
vantageously. There  would  be  more  narrow  thorough-cut  work, 
less  flexibility  and  more  time  to  reach  maximum  production. 
The  shovel,  however,  would  not  have  to  be  moved  back 

In  the  Danville,  Illinois,  coal  district  similar  stripping  is  done. 
Here  the  coal  seam  (No.  7)  is  practically  flat  and  about  6  ft.  4  in. 
thick.  At  the  Carbon  Hill  property  about  40  ft.  of  overburden 
is  being  removed  by  a  No.  270  Marion  revolving  shovel  equipped 
with  a  90  ft.  boom  and  5-cu.  yd.  dipper.  The  shovel  makes  a 
30  ft.  cut  for  a  length  of  1200  ft.  The  coal  is  loaded  into  cars  by 
model  31  shovel.  At  another  property,  a  layer  of  shale  18  to 
30  ft.  thick,  used  for  brick-making,  is  removed  from  above  the 
coal,  by  a  70-ton  Bucyrus  shovel  with  lj£  cu.  yd.  dipper.  This 
shovel,  instead  of  making  radial  or  parallel  cuts,  works  in  an 
approximate  circle,  going  round  and  round  a  given  area,  and  does 
not  have  to  be  turned.  A  similar  practice  may  often  be  noted  in 
the  Mesabi  range  pits. 

Tunnels  and  Shafts. — It  sometimes  happens  that  the  topog- 
raphy of  a  deposit  is  such  that  it  cannot  be  served  in  whole  or 
part  by  the  usual  thorough-cut  approach.  It  may  be  more 
economical  to  drive  a  tunnel  into  the  pit  or  to  connect  the  pit 
bottom  to  an  outside  shaft  by  means  of  a  drift.  In  some  cases 
the  overburden  will  be  removed  through  an  approach,  but  the 
deeper  ore  will  be  worked  by  the  "  milling  system"  and  drawn 
out  through  drifts  and  shafts. 

The  Balkan  mine  near  Crystal  Falls,  Michigan,  was  stripped 
of  loose  sandy  drift  with  drag-line  excavators  for  a  length  of, 
say,  800  ft.,  width  300  ft.,  and  depth  100  to  125  ft.  The  buckets 
dumped  into  portable  hopper  bins,  so  built  that  standard  cars 
ran  under  and  loaded  from  them.  The  loads  were  then  pulled 
out  by  dinky  engines  over  a  spiral  track.  The  underlying  iron 
ore  was  harder,  requiring  blasting.  When  the  pit  gets  too  deep 


128  STEAM  SHOVEL  MINING 

and  the  slopes  too  expensive  to  push  further  out  it  is  expected 
to  drift  under  the  orebody  from  an  outside  shaft;  from  the  drifts 
raises  will  be  run  up  to  the  top  of  the  ore,  and  down  these  the 
ore  will  be  put  for  transport  to  the  surface. 

The  Alpena  mine  at  Virginia,  Minn.,  is  partly  a  pit  mine,  partly 
an  underground  mine  and  partly  a  " milling"  mine.  The  pit 
portion  includes  ore  carrying  about  1  cu.  yd.  of  overburden  per 
ton.  The  pit  is  tracked  with  switchbacks  and  some  of  the  grades 
are  4J^  per  cent,  so  that  they  have  to  double  out  with  two  75-ton 
locomotives  hauling  four  50-ton  cars. 

The  Genoa  mine,  in  the  same  district,  but  now  worked  out, 
utilized  shaft  extraction. 

The  Zarza  lode  of  the  Tharsis  Company  in  southern  Spain  is 
in  part  mined  open-cast  by  hand.  The  topography  is  such  that 
both  overburden  and  ore  are  hoisted.  This  is  done  by  twin 
vertical  shafts  placed  at  a  safe  distance  back  from  the  brink 
of  the  open-cast. 

At  Rio  Tinto,  Spain,  inclined  planes  are  used  to  elevate  ore  from 
the  bottom  of  the  Mass  No.  1  open-cast  to  railroad  benches. 
Such  methods  are  laborious  and  expensive. 

Inclined  Planes. — The  methods  used  in  brown-coal  mining 
in  Germany1  (Leipsic,  Bonn,  Halberstadt,  Cologne,  etc.)  are 
stripping  with  the  continuous-bucket  excavator,  and  open-pit 
mining  in  which  the  loading  is  effected  by  the  " milling"  system. 
Here  the  overburden  is  sand  or  soft  sedimentaries  and  the 
mechanical  excavator  is  more  economical  than  the  shovel.  These 
deposits  present  a  great  variety  in  size  and  shape.  They  range 
from  relatively  thin  beds,  9  to  30  ft.  thick,  up  to  great  basin 
deposits  100  to  300  ft.  thick.  They  are  contained  in  clays, 
sandstones  and  marls.  Many  of  them  are  covered  by  glacial 
drift  consisting  of  fine  sand,  clay  and  light  gravel.  This  may  be 
only  a  thin  layer  from  20  to  25  ft.  thick,  or  may  range  from  75 
to  300  ft.  thick.  It  is  usually  remarkably  free  from  boulders. 
The  topography  of  the  country  is  usually  flat. 

Approaches  to  these  pits  are  invariably  short  steep  inclines 
served  by  the  chain-haulage  system.  The  reasons  assigned 
for  using  inclines  instead  of  long  gentle  slopes  as  used  in  America 
are  the  smaller  outputs,  greater  value  of  surrounding  land, 
necessity  of  preparing  the  coal  before  it  can  be  marketed,  greater 
economy  in  haulage  and  smaller  capital  investment  required. 

1  Young,  George  J.,  P.  L.  S.  M.  I.,  Feb.,  1916. 


METHODS  OF  ATTACK  129 

From  one  to  three  cuts  or  benches  each  about  25  ft.  deep  and 
sloped  at  45°  are  necessary  in  stripping.  As  soon  as  the  coal  is 
exposed  a  steep  incline  is  excavated  in  the  coal  and  extended 
until  a  working  face  of  from  50  to  100  ft.  is  obtained. 

From  the  floor  of  the  pit  thus  established,  drifts  of  small  cross- 
section  are  driven  at  intervals  of  50  ft.  into  the  bench,  and  at 
intervals  of  25  ft.  along  the  course  of  the  drift,  chutes  are 
constructed  to  the  surface.  At  the  mouth  of  each  chute  a 
crater  is  started  and  the  coal  is  worked  by  hand  into  the  chute 
by  the  milling  system. 

The  general  layout  for  opening  up  a  pit  depends  on  the  shape 
and  size  of  the  deposit.  Two  general  systems  are  used  on  the 
larged  and  thicker  deposits;  usually  the  initial  cut  is  started 
at  the  foot  of  the  main  incline  and  is  extended  parallel  with 
and  on.  the  longer  axis  of  the  deposit.  This  can  be  done  by 
starting  three  or  four  parallel  drifts  from  the  foot  of  the  incline 
and  extending  them  parallel  with  this  axis.  Mill  holes  are 
developed  and  follow  up  the  drifting.  The  ribs  are  taken  out 
and  the  floor  of  the  pit  cleared.  At  right  angles  to  the  first 
cut,  parallel  cuts  are  extended  at  intervals  of  50  ft.,  and  as 
rapidly  as  the  flanking  walls  of  the  initial  cut  permit.  Craters 
are  then  started  in  the  flanking  walls.  In  the  other  system 
the  initial  cut  is  made  transversely  to  the  main  axis,  and  from  the 
pit  floor  thus  developed,  drifts  are  driven  parallel  to  the  main 
axis  of  the  deposit,  and  the  line  of  advance  of  the  craters  is 
parallel  to  the  main  axis.  The  sequence  of  the  stripping  some- 
what influences  the  method  used  in  laying  out  a  pit. 

In  many  cases  in  the  stripping  operations  of  the  anthracite 
region  of  Pennsylvania,3  the  stripping  is  considered  too  deep 
to  be  removed  by  locomotives  and  hoisting  planes  are  re- 
sorted to.  These  are  all  single-track  planes  operated  by 
small  geared  hoisting  engines  with  a  capacity  of  about  150 
dump  cars  per  day,  or  about  the  output  of  one  shovel.  The 
practical  problem  involved  in  putting  these  planes  down  along 
the  steep  sides  of  the  average  pit  is  often  a  serious  one,  as  some 
of  them  are  anchored  on  a  slope  of  50°  to  60°  pitch  by  bars  sunk 
into  the  solid  rock  to  which  the  road-bed  is  tied.  J"hese  small 
hoists  are  suitable  for  a  one  shovel  stripping  job,  but  where 

1  Excerpts  from  Warriner,  J.  B.,  T.  A.  I.  M.  E.,  Feb.,  1917.  Also  see 
"Mining  the  Mammoth  Vein  with  Steam  Shovels,"  Helms,  D.  C.,  Coal  Age, 
Feb.  19,  1916. 


130  STEAM  SHOVEL  MINING 

two  or  more  shovels  are  in  operation  on  larger  jobs  it  would  be 
decidedly  economical  to  use  planes  equipped  with  hoists  capable 
of  handling  300  or  more  cars  per  day.  Such  planes  may  be 
either  single  or  double  tracked,  but  the  grade  should  be  main- 
tained at  about  20°,  which  is  the  present  average  for  the 
single-track  planes.  Some  figures  have  been  worked  upon  the 
comparative  cost  of  the  two  types  and  are  here  quoted. 

Length  of  plane  300  ft. 

Single  track  Double  track 

Hoist $500  (Second  hand)  $5,000  (New) 

Tracks,  track  material,  ropes,  etc 700                                 1,100 

Grading  for  hoist  and  plane 1,000                                3,000 

Hoist  house,  pipe  lines,  etc 800 

$2,200.  $9,900 

The  operating  personnel  and  costs  are  given  as  follows: 

Single  track      Double  track 

Top-men 2  3 

Bottom-men 2  3 

Locomotive  engineer 1  2 

Hoist  engineer 1  1 

Ore  dump  men ...;...,, 5  8 

Costing : 

Labor  per  day $17.88  $26.21 

Power  per  day 4.30  6.48 

Interest  and  depreciation,  15  per  cent 1 .00  4.00 

$23.18  $36.69 

Cost  per  car  @  150  and  300  cars  per  day $  0. 155         $  0. 122 

or  a  difference  of  3.3  cents  per  car. 

In  laying  out  these  stripping  pits,  the  location  of  the  limits 
of  stripping  are  set  on  a  line  where  the  normal  slope  of  overburden 
from  the  bottom  of  the  final  cut  intersects  the  surface.  Slopes 
are  calculated  on  1 :1  for  earth  of  a  clayey  nature  or  shaley  rock; 
1)^:1  or  2:1  for  sandy  ground;  vertical  for  single  cut  rock  work; 
and  J£:l  for  deeper  rock  work.  It  is  very  important  to  have 
the  foot  of  the  stripping  slope  well  back  from  the  bottom  rock 
of  the  coal  in  order  to  prevent  the  washing  of  overburden  by 
rains  into  the  exposed  vein.  The  standard  width  of  such  berms 
is  from  10  to  15ft. 

Fig.  24  illustrates  this  work  and  Figs.  25,  26  and  27  illustrate 
crop,  basin,  and  anticline  stripping,  into  which  divisions  all 
of  these  anthracite  strippings  fall.  Fig.  25,  showing  the  crop 


METHODS  OF  ATTACK 


131 


stripping,  is  interesting  in  that  it  also  shows  the  chain  pillar 
left  in  early  mining  under  the  surface  wash,  which  here  was  40 
ft.  or  more  in  thickness.  Breasts  were  driven  up  in  the  early 


7  'rack  'for 


.Track  for 


ThisCut30Ft.Wide 
in  Bottom  to  Accom- 
modate.Steam 
5hovel. 


_  _  _  _  _ 

Top  of  Rock-*       Track  for' 
No.8  Cut 


FIG.  24. — Stripping  anthracite  coal  vein. 

days  until  the  roof  caved  in,  and  were  then  abandoned.     The 
width  of  the  chain  pillar  is  at  least  150  ft.     Here  the  object  is 


_,        .  Crop  Fa  1 1 Pro/. 

5fnppin9\l3t6.0    30  Ft.  East 


1353.0 


1358.0 


Scale  of  Feet 


FIG.  25. — Stripping  anthracite  coal  veins. 


not  to  uncover  all  the  coal,  but  merely  to  remove  enough  of  the 
clay  and  rock  to  permit  the  mining  of  the  coal  from  inside  with 
minimum  loss.  To  do  this  it  is  impossible  to  drive  chutes  up  in 


132 


STEAM  SHOVEL  MINING 


the  old  vein  and,  therefore,  a  gangway  is  driven  in  a  small  under- 
lying vein  from  which  chutes  are  driven  up  to  a  point  opposite 
the  lowest  edge  of  the  chain  pillar  and  rock  holes  are  then  driven 
through  into  this  pillar. 

Fig.  26  is  of  a  large  basin  stripping,  which  was  operated  for 
several  years  (1900  to  1915)  and  shows  the  various  stages  of 


Datum  1500  ~^^n^^^      Datum/500 

FIG.  26.  —  Stripping  anthracite  coal  vein. 

excavation  characteristic  of  strippings  of  this  kind.  This  is  of  a 
virgin  vein;  the  width  is  300  ft.,  length  4,800  ft.  and  maximum 
depth  of  cover  100  ft.  The  ratio  of  cubic  yards  of  cover  per 
ton  of  coal  is  3.46  to  1. 

Fig.    27    illustrates    an    anticlinal    stripping    of    a    worked- 
over  area  in  which  it  is  estimated  that  60  to  70  per  cent,  of  the 


Stripping  &  Level  El.  1331.  6  . 

stri 


FIG.  27. — Stripping  anthracite  coal  vein. 

coal  remains.  Upon  this  estimate  depends  its  profitableness, 
as  it  has  been  undertaken  primarily  to  form  a  final  barrier 
against  a  fire  that  has  been  raging  to  the  east  of  it  for  many 
years.  The  vein  is  55  ft.  thick  and  is  on  a  20°  pitch.  It  has 


METHODS  OF  ATTACK 


133 


134  STEAM  SHOVEL  MINING 

been  robbed  and  re-robbed,  and  robbed  again,  but  because  of 
its  thickness  and  unhandy  pitch,  as  well  as  the  time  of  mining 
in  the  early  '50's,  it  is  thought  that  not  over  35  per  cent,  of  the 
coal  has  been  extracted.  Fig.  28  shows  a  plan  of  this  stripping. 

In  passing  it  may  be  mentioned  that  many  of  the  open  pit 
coal  mines  have  inclines  leading  from  the  pit  bottom,  or  from  the 
end  of  the  haulage  system,  to  the  tops  of  tipples,  from  which  the 
coal  is  graded,  cleaned,  and  loaded  into  standard  gauge  cars. 

Milling  System.* — The  best  condition  for  the  application 
of  the  system  of  milling  is  believed  to  be  where  an  orebody  is  of 
medium  size  suitable  for  stripping,  but  where  it  would  not  admit 
of  economical  locomotive  haulage  of  the  ore.  The  relative  depth 
of  overburden  and  ore,  the  space  and  facilities  for  trackage  and 
approaches  and  the  relative  outlay  for  equipment  and  develop- 
ment, are  the  determining  factors  for  choosing  between  " milling" 
and  "shoveling."  The  advantages  of  the  former  are  smaller 
initial  expenditure,  as  the  entire  orebody  need  not  be  stripped, 
a  comparatively  small  amount  of  stripping  to  expose  enough 
ore  to  begin  production,  less  waste  room  is  required  and  the 
approach  to  deep  ore  is  avoided.  Offsetting  these  are  the  expense 
of  shaft,  drifts,  raises  and  attendant  equipment,  liability  of 
flooding  the  mills  with  sand  and  slime  during  heavy  storms  and 
irregularity  of  production  due  to  weather  conditions  and  oc- 
casionally due  to  hanging  up  of  mills. 

Milling  permits  the  recovery  of  practically  all  of  the  ore,  is  more 
economical  than  underground  mining,  and  is  perhaps  a  little 
safer.  It  is  subject  to  the  accidents  incident  to  its  limited  under- 
ground work  and  to  the  blasting  in  the  open,  but  the  greatest 
danger  is  when  men  are  carried  into  the  chutes  by  slides,  not- 
withstanding their  attachment  ropes. 

In  some  cases  shovels  are  used  to  mine  the  bottom  layer  of  ore, 
or  to  dig  the  ore  remaining  in  the  hog-backs  and  cones,  dropping 
it  into  the  mills. 

In  other  cases  the  mills  are  eliminated  and  the  shovel  loads 
directly  into  cars  which  are  then  trammed  to  a  central  raise 
feeding  a  shaft  pocket.  Fresh  shovel  cuts  are  started  in  pits 
of  this  kind  by  bringing  in  drifts  from  the  shaft  at  the  desired 
elevation  and  making  an  opening  for  the  shovel  to  begin  a 
a  new  cut. 

1  It  is  assumed  this  system  is  understood.  See  "Iron  Mining  in  Minne- 
sota," C.  E.  Van  Barneveld. 


CHAPTER  IV 
DRILLING  AND  BLASTING 

Material  to  be  excavated  with  power  shovels  should  be  loose 
enough  to  be  dug  easily  and  without  causing  excessive  strains 
and  wracking  on  the  shovels.  Some  material  occurs  naturally 
in  this  condition  so  that  no  further  breaking  up  is  necessary. 
Other  material  can  be  dug  without  preliminary  loosening  but 
the  saving  in  the  cost  of  loosening  is  more  than  offset  by  the 
decreased  output  and  by  increased  wear  and  tear  on  the  equip- 
ment. Still  a  third  class  of  material  must  be  blasted  in  order  to 
be  excavated  at  all.  Some  class  of  explosive  is  now  universally 
used  to  accomplish  this,  and,  in  order  to  prepare  chambers  for 
loading,  hand-drills,  machine-drills,  churn-drills,  gopher  holes 
or  pit-shafts  and  drifts  are  employed. 

Hand -drills. — On  the  iron  ranges  of  Minnesota  the  usual 
overburden  is  a  glacial  drift,  frozen  in  the  winter  time,  and  often 
containing  huge  hard  granite  boulders  ranging  from  3  to  12  ft. 
in  diameter.  These  are  " chained  out"  by  the  shovels  and  placed 
on  one  side  in  their  wake  to  be  block-holed.  These  boulders  are 
drilled  by  hand,  using  %  in.  steel.  The  holes  are  from  12  to  18 
inches  deep  and  are  loaded  with  a  stick  of  60  per  cent,  dynamite. 
The  drilling  is  done  on  contract  at  20  cents  per  foot,  and  an 
average  day's  work  is  from  12  to  15  feet.  When  the  overburden 
is  frozen  jumper  drills,  heated  to  a  dull  red,  are  used  to  put  down 
shallow  holes  called  "top"  holes.  In  deeply  frozen  ground  steam- 
points  have  been  used.  These  holes  are  put  down  from  3  to  6 
ft.  through  the  frost.  They  are  charged  with  from  six  to  eight 
pounds  of  Du  Pont  black  powder.  In  some  cases  the  surface 
of  the  ground  is  broken  up  before  frost  sets  in  by  drilling  holes 
3  to  5  ft.  deep  and  shooting  them  with  light  charges. 

In  most  of  the  open  pit  iron  mines  requiring  blasting,  it  is 
customary  to  blast  the  ore  banks  ahead  of  the  shovels.  Top 
holes  are  used  for  this  purpose,  excepting  where  there  is  rock 
capping  over  the  ore.  In  the  latter  case  gopher  holes  are  drilled. 
Top  holes  are  "  jumped"  or  churned  by  gangs  of  drillers  working 

135 


136  STEAM  SHOVEL  MINING 

in  groups  of  2  or  4  men.  The  drills  are  made  of  1  in.  round  or 
hexagonal  steel,  chisel  pointed  on  both  ends.  A  heavy  iron 
cross  handle  or  yoke  26  in.  long  is  slipped  over  the  drill  and 
fastened  in  place  with  a  6-inch  steel  wedge. 

The  spacing  of  these  holes  depends  on  the  hardness  and  texture 
of  the  ore/  the  height  of  the  bank  and  the  width  of  the  cut  to  be 
taken.  In  average  ore  with  banks  from  15  to  25  ft.  high,  the 
holes  are  usually  spaced  15  to  20  feet  apart  and  about  the  same 
distance  back  from  the  crest  of  the  bank.  They  should  bottom 
a  foot  or  two  below  grade  so  that  there  will  be  no  " tight"  ore 
on  the  bottom.  The  limiting  depth  of  these  holes  is  22  ft. 
In  average  ground  a  15  ft.  top  hole  when  finished,  would  be 
sprung  with  2  to  6  sticks  of  60  per  cent,  dynamite,  then'loaded 
with  black  powder  and  fired.  If  several  holes  of  this  depth  were 
to  be  blasted  in  series,  the  charge  would  consist  of  1  to  1^  kegs 
(of  25  Ib.)  of  black  powder.  If  the  holes  are  to  be  shot  separately, 
as  is  sometimes  necessary  when  the  bank  is  high  and  the  loading 
track  close  in  to  the  toe,  the  charge  should  be  slightly  increased. 
Top  holes  are  usually  fired  in  series  of  not  more  than  five  at  a 
time,  using  a  blasting  machine.^  In  some  cases  safety  regulations 
require  that  holes  be  fired  separately. 

A  gang  of  jump-drillers  will  average  50  ft.  of  hole  per  man  per 
day  in  ore;  good  jump-drillers  are,  however,  rather  scarce.  Hand- 
drills  are  generally  being  replaced  by  machine  drills. 

It  may  be  mentioned  further  regarding  the  spacing  of  holes 
(hand  or  machine  drilled)  that  rules  have  been  made  whereby 
both  the  spacing  back  from  the  face  and  the  distance  apart 
have  varied  from  distances  equal  to  the  depth  of  holes  to  one- 
half  their  depth;  or  their  distance  apart  may  be  even  further 
decreased.  Such'  rules  will  serve  to  experiment  with  until 
the  material  is  broken  to  a  suitable  size.  Obviously  the  spacing 
will  have  a  marked  effect  on  the  cost  of  breaking  as  it  involves 
both  the  cost  of  drilling  and  cost  of  explosive  per  cu.  yd.  A 
fair  range  of  examples  of  such  work  may  be  found  carrying 
from  0.25  to  1.25  ft.  of  hole  and  from  0.30  to  0.70  Ib.  of  40  per 
cent,  dynamite  per  cu.  yd.  of  material  broken. 

Machine-drills. — At  the  Utah  Copper  and  Chino  Copper 
mines  machine  drills  have  been  extensively  used.  Fig.  29  shows 
the  method  of  drilling  and  blasting  a  70-foot  bank  and  Fig.  30  the 
remarkable  240-foot  bank,  both  at  the  Utah  mine.  Churn-drills 
will  be  substituted  for  some  of  this  work  as  the  levels  are  widened 


DRILLING  AND  BLASTING  137 

out  to  80  or  100  feet.  The  general  method  now  is  to  drill  toe 
holes  with  a  maximum  depth  of  25  feet,  spaced  from  15  to  30  ft. 
apart  (average  20  feet),  depending  on  conditions.  It  is  usual  to 
shoot  one  hole  at  a  time,  taking  advantage  of  the  face  of  rock 
facing  the  shovel  and  facing  the  main  bank,  thus  giving  two 
open  faces;  also  the  broken  rock  lies  closer  in,  which  is  a  decided 
advantage  on  these  narrow  benches.  Frequently  two,  three  or 
even  as  many  as  six  holes  are  shot  at  a  time,  advantage  being 
taken  of  seams,  slips  and  the  appearance  of  the  face  to  be 
broken.  In  single  or  multiple  shots  there  is  no  appreciable 
difference  in  the  condition  of  the  blasted  ground,  the  material 
can  be  handled  with 'equal  ease  and  the  banks  are  equally  safe. 
The  holes  are  drilled  ahead  of  the  work,  and  preceding  shots 


; 

i       i              ! 

i 

.    .    . 

:    :    :    : 

:    sg                     A 

Conditions  -  Hard  Blocky  Porphyry 

Ml  Holes  Sprung  2  to  4  times  with  ~~SfoSO  tb.  of  60  Per  Cent  Red  H  Powder. 
Holes  a&b Loaded  w/ffy 200  toSOOIb. of  60  PerCent  Red  H  Powder 
Holes  c  Loaded  with  150  to  250  Ib.  of  60  Per  Cent  Red  H  Powder 
Holes  d~  Drilled  only  when  Ground  Fails  to  Break  from  Hole  a^ 
Loaded  with  ISO  to  200  Ib.  of  60  Per  Cent  Red  H  Powder 
Order  of  Blasting  a,c,d,  b. 

FIG.  29. — Drilling  and  blasting  70-ft.  bank;  tripod  drilling. 

do  not  destroy  holes  already  made.  One  of  the  most  important 
points  is  to  see  that  the  hole  is  drilled  a  little  below  grade,  and 
that  the  powder  is  charged  at  the  end  of  the  hole.  At  this 
mine,  it  has  been  found  that  single-hole  shots  bring  down  plenty 
qf  material  to  last  one  shift  so  they  do  not  affect  the  delays 
to  the  individual  shovels.  Blasting  is  done  at  stated  times,  viz., 
in  the  morning,  at  noon  and  at  night.  The  shovels  are  brought 
to  a  safe  position  when  shots  are  made. 

Details  of  the  drilling  and  loading  of  the  holes  are  shown  on 
Figs.  29  and  30.  About  two  cubic  yards  of  rock  are  broken 
per  pound  of  powder  consumed,  including  the  powder  used  in 
breaking  up  large  boulclers.  The  records  show  that  4J£  to  5 
tons  of  ore  and  waste  are  broken  per  pound  of  powder  consumed. 
The  question  of  block-holing  large  rocks  versus  dobying  is  en- 
tirely one  of  delays  to  operations.  Whenever  convenient,  block- 


138 


STEAM  SHOVEL  MINING 


holing  is  preferred,  but  generally  the  large  rocks  are  laid  aside 
and  dobied  at  the  regular  times  for  shooting. 

At  the  Chino  property  the  bank  bottoms  are  drilled  with 
air  drills,  but  most  of  the  regular  bank  shooting  is  done  from 
churn-drill  holes. 

In  digging  the  Panama  Canal  many  variable  mining  conditions 
were  met;  subaqueous  work  with  drill  barges;  drilling  in  the  dry 
for  dredging  where  the  water  was  turned  in  after  blasting;  blast- 
ing for  shovels  through  different  cuts;  blasting  rock  to  be  crushed 
for  concrete;  core  rock  for  breakwaters  and  large  rock  for  their 
armoring. 

In  working  on  50-foot  banks  the  method  was  to  drill  lifting 
holes  26  ft.  deep  with  7  foot  spacing;  then  from  the  top  and  about 


F  LEVEL 


'--- 


3'MO1 


Distances 


8     8     8 


depending  on  the  way  the 
Hole  of  the  Toe  Breaks. 

Holes 

Sprunq2it>4  Times  with 
StoSolb.  of  60  Percent 
Red  H  Powder. 

Charge 

200  to  300  Ib.  of  60  PerCent 
ffedH  Powder 


FIG.  30. — Drilling  and  blasting  240-ft.  bank;  tripod  drilling. 

14  ft.  from  the  face  perpendicular  holes  28  ft.  deep  with  8  ft. 
spacing.  This  assumes  the  toe  to  be  26  ft.  from  the  charge,  if 
the  down  hole  was  projected  to  bottom  grade.  The  charges 
were  of  60  per  cent,  dynamite.  The  material  was  satisfactorily 
broken  for  shovel  and  crusher  handling. 

At  Sosa  Hill  quarry,  where  the  highest  point  on  the  bank  is 
about  250  ft.,  as  much  as  25,000  cu.  yd.  were  broken  at  one  blast. 
Here  the  lifting  holes  were  26  ft.  deep  and  the  bank  was  cut  into 
4  or  5  benches  from  which  28  ft.  vertical  holes  were  drilled. 
The  lifting  holes  were  loaded  with  from  100  to  200  Ibs.  of  60 
per  cent,  dynamite,  and  all  the  down  holes  with  from  20  to  30 
Ibs.  of  45  per  cent,  dynamite.  After  these  blasts,  all  of  the  rock 
was  dug  from  the  bottom  level. 


DRILLING  AND  BLASTING  139 

In  comparing  single  and  multiple  hole  shots,  it  was  the  opinion 
at  Panama  that  the  latter  were  most  advantageous;  that  single 
holes  required  at  least  one-third  more  powder;  that  the  blasted 
ground  was  much  easier  to  handle  'when  holes  were  shot  in 
multiple;  that  in  case  one  hole  in  a  larger  series  was  caved  or 
lost,  the  holes  flanking  it  broke  up  the  ground  enough  for  the 
shovel  to  dig  it  and  that  the  cost  of  drilling  the  next  hole  was 
less  because  there  was  no  chance  of  one  hole  breaking  into  the 
ground  where  the  next  one  was  to  be  drilled,  or,  if  the  ground 
ahead  had  already  been  drilled,  of  spoiling  holes.  This  was 
especially  true  in  using  both  lifting  and  down  holes;  the  blasted 
bank  was  left  in  better  shape  and  the  shovel  output  was  much 
greater.  Multiple  shots  carrying  as  many  as  180  twenty-six 
foot  tripod  drill  holes  and  150  fifty-five  foot  churn  drill  holes 
were  shot  as  once.  Single  holes  were  only  used  for  loosening 
up  hard  spots  found  in  front  of  the  shovel,  or  when  the  shot 
was  less  than  100  ft.  from  valuable  structures,  or  where  a  quantity 
of  water  might  break  through  with  a  heavy  shot. 

It  was  also  considered  that  dobying  saved  time  but  block- 
holing  was  safer.  Large .  pieces  which  the  shovels  could  not 
handle  were  broken  at  once,  usually  by  dobying. 

On  the  iron  ranges  a  number  of  mining  companies  are  using 
machine  drills  instead  of  " jumper"  drills  for  putting  down  top 
holes. 

The  use  of  air  machines  in  large  open-pits  necessitates  either 
the  building  of  a  compressor  plant  and  extending  pipe  lines 
through  the  pit  or  equipping  each  shovel  with  a  compound  air 
pump.  The  latter  arrangement  does  away  with  the  shifting 
of  pipe  lines  as  the  benches  are  worked  back,  and  eliminates 
any  trouble  incident  to  the  freezing  of  air  lines.  Furthermore, 
an^J  individual  air  pump  is  advantageous  when  the  shovel  is 
moved  from  ore  to  stripping,  in  that  it  can  furnish  power  to 
operate  jackhammer  drills  for  block-holing  boulders,  obviating 
the  necessity  of  using  hand  drills  or  dobying. 

With  the  D-113  Ingersoll-Rand  drill  an  average  of  90  feet 
per  shift  has  been  made  in  the  Mesabi  district.  This  footage 
is  equivalent  to  45  ft.  per  man  per  day — two  men  being  on  the 
drill — as  against  50  ft.  per  man  per  day  with  the  jumper  drills. 
The  advantages  with  the  machine  drills,  however,  are  that  they 
drill  through  rock  seams  readily,  and  can  drill  to  a  depth  of  28 


140  STEAM  SHOVEL  MINING 

or  30  ft.  as  against  22  ft.  with  jumpers;  also  it  is  easier  to  obtain 
crews  for  the  machine  drills. 

The  loading  and  blasting  of  these  holes  is  the  same  as  was 
mentioned  above  under  hand  drills. 

On  stripping  rock  in  the  Pennsylvania  anthracite  region,  holes 
12  ft.  or  less  in  depth  are  drilled  with  steam  tripod  drills  which 
make  about  7  ft.  per  hour  in  solid  rock.  The  holes  are  usually 
arranged  in  3  parallel  rows  with  a  staggered  spacing  of  from 
12  to  20  ft.  They  are  fired  in  batteries  of  15  to  25  or  more. 
From  3  to  8  sticks  of  40  per  cent,  dynamite  are  used  to  spring 
each  hole,  which  operation  may  be  necessary  two  or  three  times. 
They  are  then  charged  with  black  powder,  filling  the  chamber 
and  about  2  ft.  up  the  remainder  of  the  barrel.  The  holes  are 
tamped  with  clay  or  coal  dirt.  For  25  to  30  ft.  holes  "Star" 
churn  drills  are  employed  using  a  4  in.  bit.  These  make  about 
3Jtj  ft.  per  hour  in  solid  rock.  The  average  cost  for  drilling  and 
blasting  per  cu.  yd.  of  rock  excavated  is  given  as 

Labor  drilling  and  charging,  depreciation,  equipment,  etc.  $0.045 — $0.065 

Powder 0. 055—  0. 080 

$0.100—10.145 

Temple-Ingersoll  percussion  drills,  operated  by  a  portable 
electric-air  pulsator,  have  been  successfully  used  in  drilling  holes 
for  loosening  up  the  stripped  coal  beds  in  the  Danville,  111. 
district.1  In  one  case  on  a  coal  bed  5J^  ft.  thick,  1%  m-  holes 
were  placed  5^  ft.  back  of  the  coal  face  and  spaced  5  to  6  ft. 
These  were  each  charged  with  1%  to  2  pints  of  black  powder. 
On  another  job  these  machines  drilled  3  in.  holes  spaced  6  to  7 
feet  apart,  and  the  charge  in  each  was  about  lj^  quarts  of  black 
powder.  A  push-down  blasting  machine  fires  the  charges. 
These  holes  are  so  loaded  that  they  merely  loosen  the  coal  but 
do  not  throw  it  about.  A  25  Ib.  keg  of  powder  loosens  about  100 
tons  of  coal,  which  is  then  loaded  into  mine  cars  with  a  small 
shovel.  At  another  mine,  an  Ingersoll-Rand  portable  electric- 
ally driven  compressor  furnishes  air  for  Jackhammer  drills 
which  put  down  1%  in.  holes  about  6  ft.  deep.  Here  the  coal 
averages  6  ft.  4  in.  in  thickness.  The  holes  are  spaced  6J^  ft. 
apart  and  are  placed  6H  ft.  back  of  the  face. 

Churn  drills. — Where  conditions  permit  the  use  of  churn 
well-drills,  they  have  largely  replaced  hand  and  tripod  drills. 

^'Steam-shovel  Coal  stripping  in  the  Danville  District."— Coa I  Age, 
March  11,  1916. 


DRILLING  AND  BLASTING    * 


141 


At  the  Utah  Copper  Company's  mine  few  churn  drills  are 
used  because  of  the  narrowness  of  the  benches.  An  interesting 
combination  of  the  use  of  tripod  drills  and  churn  drills  is  shown 
on  Fig.  31.  Here  the  240-foot  bank  is  shot  by  means  of  churn 
drill  holes  from  the  bench  supplemented  by  tripod  drill  holes  at 
the  toe  and  part  way  up  the  bank.  Details  of  the  arrangement 
and  loading  are  given  on  the  figure. 

At  the  mines  of  the  Chino  Copper  Company  most  of  the 
blasting  is  done  by  means  of  churn  drill  holes.  Only  one  of 
these  is  blasted  at  a  time,  as  it  has  been  found  t{iat  large  blasts 
of  several  holes  each  are  not  advantageous  here.  The  bottoms 


(e'Key stone  Holes 
I  Sprung  and Loaded 
<  with  50 1 b.  of  60  Per  Cent 


»-K- 


Li  ><  WITH  suiD.  or  wwrLenr 
r  \RedHPowderand7f o/O 
-to    4<  to    A  to    J     \Cans  of  Black  Powder 
30'        3^7'         5^' 


l> 

I 


(if  necessary  20  'to  25 ' 
r-  )  Deep,  ISO  to  200  lb. 
''-\  of  60  Per  Cent  Red 

\HPowder 


,  200  to  300 1  b.  of  60  Per  Cent 
Red  H  Powder 


. 

'••....  ISO  to  200 1  b.  of  60  Per  Cent 
Red  H  Powder 

FIG.  31.— Drilling  and  blasting  240-ft.  bank;  well  drilling.  j 

are  drilled  with  tripod  drills.  The  churn  drill  holes  are  put  down 
from  25  to  60  feet  deep,  and  "sprung"  by  exploding  several 
light  charges  of  dynamite  in  the  bottom.  This  chambering  is 
clone  four  or  five  times  with  increasingly  larger  amounts  of 
powder  each  time;  e.g.  the  first  time  with  5  sticks,  the  second  with 
10,  the  third  with  20  and  the  fourth  with  25  to  30  sticks.  Gen- 
erally 40  per  cent  dynamite  is  used  for  this  purpose.  By  aid 
of  a  hand-mirror  the  sunlight  can  be  reflected  into  a  hole  to  a 
depth  of  25  ft.  or  more  and  this  is  of  assistance  to  the  loader. 
After  the  hole  has  been  chambered  sufficiently,  it  is  loaded  for 
blasting.  The  charge  depends  on  the  depth  of  the  hole,  hardness 


142  STEAM  SHOVEL  MINING 

of  the  ground,  burden  carried  and  track  conditions.  Two  aver- 
age charges  are  given  as  follows;  (1)  a  28  ft.  hole  on  a  terrace  of 
ore,  138  Ibs.  of  40  per  cent,  dynamite  and  100  Ibs.  Trojan  granu- 
lated powder  No.  2;  (2)  a  50  ft.  hole  on  a  higher  terrace  of  ore, 
170  Ibs.  of  40  per  cent,  dynamite  and  200  Ibs.  of  Trojan  No.  2. 
The  holes  are  usually  drilled  from  3  to  5  ft.  below  grade  but  in 
case  the  ground  breaks  badly,  horizontal  tripod  drill  holes  are 
drilled  and  blasted  to  level  up  the  surface  for  the  advancing 
shovel  track.  Warning  of  a  shot  is  given  by  whistle  signals 
from  the  shovel  and  the  crews  in  the  vicinity  seek  shelter  behind 
portable  steel  shields.  Some  interesting  detonation  experiments 
were  carried  out  at  this  property  between  \Y±  in.  X  8  in. — 40 
per  cent.  Ropauno  Gelatin  Dupont  powder  and  1J^  in.  X  8  in. 
Trojan  powder.  No.  8  blasting  caps  were  used  and  placed  as 
nearly  as  possible  in  the  center  of  the  stick  of  powder  used  as  a 
primer.  The  tests  were  carefully  conducted.  The  conclusions 
reached  were  that  the  Gelatin  powder  Jf  relatively  easy  of  de- 
tonation and  would  explode  in  all  cases  where  the  powder  is  close 
enough  together  for  a  portion  of  the  stick  to  be  destroyed;  on 
the  other  hand  the  Trojan  detonates  with  difficulty  and  requires 
to  be  in  close  contact  with  the  primer  or  other  detonated  sticks. 
This  is  based  on  small  charges  unconfmed.  These  conclusions 
are  of  interest  where  the  shooting  out  of  missed  holes  would  be 
attempted  by  the  usual  method  of  drilling  and  shooting  another 
hole  in  close  proximity  to  the  missed  hole.  It  seems  doubtful 
if  this  could  be  successfully  accomplished  with  Trojan  powder. 
Again  in  badly  ravelled  or  broken  holes,  it  would  seem  that  there 
might  remain  unexploded  sticks  which  had  not  been  loaded  in 
close  contact  with  the  powder  immediately  surrounding  the 
primer.  Actual  conditions  of  confinement  in  a  drill-hole,  how- 
ever, might  modify  these  conclusions. 

The  open-pit  mines  of  the  Nevada  Consolidated  Copper  Com- 
pany are  in  a  leached  highly  altered  monzonite  porphyry.  Prac- 
tically all  of  this  material  requires  blasting  and  this  is  done  by 
putting  down  6  in.  churn  drill  holes.  These  are  all  drilled  from  3 
to  5  ft.  below  grade,  i.e.,  a  hole  55  ft.  deep  is  drilled  for  a  bank 
50  ft.  high.  This  is  important  as  it  removes  most  of  the  danger 
of  leaving  unbroken  rock  on  the  bottom.  The  holes  are  spaced 
about  two-thirds  of  their  depth  or  say  37  ft.  apart  for  55  ft. 
depth.  The  slopes  of  the  banks  average  about  45°,  thus  the 
edge  is  at  a  horizontal  distance  back  of  the  toe  equal  to  the  height 


DRILLING  AND  BLASTING  143 

of  the  bank.  Holes  are  drilled  as  close  to  the  upper  edge  as 
convenient  or,  say,  10  ft.  back,  making  them  bottom  60  ft .  back 
of  the  bank  toe.  When  a  drill  has  moved  onto  a  hole  location,  the 
rear  wheels  are  leveled  transversely  by  running  one  wheel  on 
blocking  if  necessary.  The  wheels  are  then  blocked  to  prevent 
the  drill  from  moving  and  the  traction  pin  is  removed.  Two 
track  jacks  are  placed  beneath  the  front  end  of  the  bed,  and  are 
used  to  relieve  the  front  wheels  of  the  weight  they  support  and 
to  level  the  front  end  transversely.  Such  leveling  is  impera- 
tive in  order  to  keep  the  belt  on  the  pulleys  when  running.  No 
attention  need  be  paid  to  longitudinal  leveling  as  drills  are  some- 
times operated  with  the  tools  hanging  almost  to  the  end  of  the 
"  A" frame  tool  guide,  and,  again,  with  scarcely  any  room  between 
them  and  the  front  of  the  machine,  but  it  is  desirable  to  have  at 
least  2J^  ft.  between  the  front  of  the  drill  and  the  tools.  Much 
time,  however,  should  not  be  spent  in  longitudinal  leveling.  A 
four-foot  piece  of  7%  in.  casing  called  a  "conductor"  is  used  to 
guide  the  tools  when  drilling  is  started.  This  has  two  coils  of 
old  2  in.  drill  cable  wrapped  around  it  to  prevent  it  from  sinking 
into  the  hole,  and  also  to  furnish  a  hold  for  removing  it  when  the 
hole  is  finished,)  As  mentioned  above,  the  ground  is  blasted  from 
3  to  5  feet  below  grade,  so  for  a  few  feet  the  holes  are  drilled  in 
broken  ground  remaining  from  previous  shooting,  and  the  "  con- 
ductor" protects  this  section  of  the  hole  from  caving.  The  drill 
is  run  slowly  until  the  hole  is  4  or  5  ft.  deep,  then  it  is  speeded 
up  to  about  58  drops  per  minute.  The  hole  is  baled  out  every 
2J£  or  3  ft.  and  the  sludge  is  allowed  to  run  down  the  bank  below, 
unless  it  is  to  be  sampled.  After  the  hole  is  completed  the  tools 
are  pulled  up  and  are  tied  to  the  bed  of  the  machine  to  prevent 
them  from  swinging  while  the  drill  is  moving.  The  dart  of  the 
bailer  is  tied  to  the  rope  on  the  conductor  which  is  then  pulled 
out  of  the  hole.  The  bailer,  or  sand  pump,  is  hauled  up  into 
the  "A"  frame,  to  prevent  it  from  swinging  enough  to  do  damage. 
The  track  jacks  are  removed,  the  traction  pin  put  in  place,  the 
blocks  removed  from  the  wheels  and  the  drill  moved  to  the  next 
spot. 

The  drill  crew  is  followed  by  the  blasting  crew.  The  powder 
foreman  carefully  notes  the  depth  of  the  hole,  friability  of  the 
material  and  the  burden  carried,  and  from  these  decides  what 
charge  shall  be  used.  Chambering  is  started  with  a  light  charge 
and  the  amount  tripled  for  each  succeeding  chambering  charge. 


144  STEAM  SHOVEL  MINING 

For  a  hole  45  ft.  deep,  say,  10  sticks  of  60  per  cent,  semi-gelatin 
Red  Cross  powder  would  be  used  for  the  first  charge,  30  sticks 
for  the  second  chambering  and  90  sticks  for  the  third  J  When 
using  black  powder  for  the  blasting  charge,  about  25  Ibs.  were 
allowed  per  foot  of  hole.  For  holes  90  ft.  in  depth,  chambering 
is  started  with  about  25  Ibs.  of  60  per  cent.  R.C.  powder  and  in- 
creased by  doubling  or  tripling  the  amount  for  successive  cham- 
bering shots.  Water  is  used  for  tamping  these  chamber  charges, 
say,  20  gal.  for  the  first  charge  and  triple  the  quantity  for  each 
succeeding  charge.  About  25  Ib.  of  black  powder  were  allowed 
per  foot  of  hole  in  the  blasting  charge. 

In  determining  the  progress  of  chambering  it  has  been  found 
helpful  to  use  a  sounding  rope.  This  consists  of  a  piece  of  win- 
dow-pulley spot  cord  about  75  ft.  long  to  one  end  of  which  is 
attached  a  piece  of  wood  about  4  in.  in  diameter  by  3  ft.  long. 
This  club  is  let  down  to  the  bottom  of  the  hole  and  permitted  to 
fall  over  from  side  to  side  in  such  a  manner  that  the  bottom  en- 
largement may  be  felt  out. 

In  charging  holes  a  50  ft.  length  of  6  in.  diameter  rubber-lined 
tuyere  tubing  is  slipped  over  the  cylindrical  spout  of  a  galvanized 
sheet  iron  funnel.  This  provides  a  -smooth  lining  for  the  wall 
of  the  hole  preventing  powder  from  lodging  in  seams  or  fissures 
and  also  preventing  fragments  of  the  wall  from  being  knocked 
off  by  the  falling  powder.  After  placing  this  sleeve  in  the  hole, 
the  sounding  line  is  fed  down,  and  then  as  the  powder  is  run  down, 
the  sounding  line  is  jigged  up  and  down  on  top  of  the  powder 
assisting  it  to  be  closely  seated  but  not  tamped.  This  line  con- 
stantly shows  to  what  extent  the  bore  has  been  filled  with  powder 
and  indicates  the  extent  of  chambering.  When  the  required 
charge  has  been  loaded,  the  sounder  and  sleeve  are  removed  and 
the  remainder  of  the  bore  is  filled  to  the  top  with  fine  dirt  or  sand. 

It  was  found  that  a  blast-hole  would  break  the  ground  in 
back  of  it  about  one-quarter  of  the  distance  it  broke  in  front 
or  on  the  side  offering  the  least  resistance.  All  blasting  and 
chambering  is  done  using  No.  8  electric  exploders. 

Fig.  32  illustrates  a  hole  being  sprung. 

The  following  percentages  of  explosives  were  used  in  the 
earlier  operations  of  1912  and  later  operations  of  1916,  by  the 
Nevada  Consolidated  Copper  Company. 


DRILLING  AND  BLASTING 


145 


Explosive 


1912 
per  cent. 

27 
23 
15 


F.  F.  black  powder 

Stick  Trojan  (3V£  in.  .  X  3%  in.,  mostly) 

Bag  or  granu.ar  Trojan 

Hercules  R.  R.  P - 

Hercules  3^  in.  X  3^  in.— 40  per  cent 30 

Hercules  1H  in.  X  1M  in.  Red  "H" 

Hercules  40  per  cent  (1^  in.  X  4  in.,  mostly) 

Gelatin  and  semi-gelatin  60  per  cent 2 

Red  Cross  40  per  cent 2 


1916 
per  cent. 

4 

69 
4 
8 
3 
7 
4 


FIG.  32. — Drill-hole  being  sprung. 

It  will  be  noted  that  the  black  powder  has  been  displaced 
by   the   more   efficient   Trojan   powder.     Experiments   carried 


10 


146  STEAM  SHOVEL  MINING 

out  using  Trojan  40  per  cent.  vs.  Hercules  40  per  cent,  indicated 
that  the  breakage  per  pound  of  Hercules  was  higher  than  the 
Trojan;  that  the  cost  per  pound  of  the  Trojan  was  less;  that  the 
cost  per  yard  of  material  broken  was  about  the  same  in  both 
cases;  that  the  Trojan  worked  well  in  cold  weather,  requiring  no 
thawing,  and  was  held  in  consequence  to  be  more  convenient 
and  safer  to  handle. 

About  0.6  Ib.  of  powder  were  required  per  cu.  yd.  of  material 
broken,  including  explosives  used  in  dobying  boulders. 

Varied  and  interesting  experience  in  the  loading  and  shooting 
of  well-drill  holes  has  been  given  by  S.  R.  Russell  C.  E.1 

Some  of  the  following  brief  records  of  blasts  in  different  sec- 
tions of  the  country  are  quoted  from  him.  An  average  of  4  to  6 
tons  of  stone  per  pound  of  explosive  is  about  what  should  be 
expected  in  blasting  deep  holes. 

A  blast  in  a  limestone  quarry  in  Tennessee,  stone  used  for 
ballast  and  commerical  purposes,  consisted  of  sixteen  5^  in. 
holes  of  average  depth  of  75  feet.  Holes  were  spaced  18  ft. 
apart  with  average  face  burden  of  22  ft.  Charge,  3750  Ib. 
of  60  per  cent,  and  3700  Ib.  of  40  per  cent.  L.  F.  dynamite. 
Produced  5.7  tons  of  rocks  per  pound  of  explosive. 

A  blast  in  cement  rock  in  Pennsylvania  consisted  of  fourteen 
5%  in.  holes;  average  depth  86  feet;  spaced  18  feet  apart  with 
a  face  burden  of  30  feet  charge,  4850  Ib.  of  60  per  cent,  and 
3250  Ib.  of  40  per  cent,  dynamite.  Produced  55,000  tons  or 
6.8  tons  per  pound  of  explosive. 

A  blast  in  a  Kentucky  limestone  quarry,  stone  used  for  ballast, 
consisted  of  nine  holes;  average  depth  50  ft.;  spaced  18  ft.  apart 
and  25  ft.  back.  Charge,  3250  Ib.  of  40  per  cent,  dynamite, 
produced  16,200  tons  of  rock  or  5  tons  per  pound. 

A  blast  in  an  Oklahoma  quarry,  stone  used  for  railroad  ballast, 
consisted  of  eight  holes  95  ft.  deep;  spaced  28  ft.  apart;  average 
face  burden  33  ft.  Charge,  2200  Ib.  of  blasting  gelatin,  3350  Ib. 
of  60  per  cent,  and  1250  Ib.  of  40  per  cent,  dynamite.  Produced 
62,000  tons  for  6800  Ib.  of  explosive,  or  9  tons  per  pound. 

The  above  blast  is  criticised  as  being  badly  balanced,  neces- 
sitating use  of  very  strong  expensive  explosive  at  bottom,  making 
the  cost  per  ton  as  high  or  higher  than  had  the  blast  been  better 
balanced. 

1  Blast  Hole  Drilling — Keystone  Driller  Magazine  First  Edition  and  Du 
Pont  Magazine,  August,  1916. 


DRILLING  AND  BLASTING  147 


A  blast  made  in  iron  ore  consisted  of  twenty-six  5j£  in.  holes 
of  average  depth  of  84  feet;  spacing  15  ft.  X  15  ft.  Holes  were 
triple  loaded,  fired  with  Cordeau  and  one  electric  blasting  cap. 
Charge,  8500  Ib.  of  40  per  cent,  dynamite  were  used,  producing 
50,000  tons  of  ore  or  5  tons  per  pound  of  explosive.  • 

A  blast  made  in  cement  rock  in  New  Jersey  consisted  of  eleven 
holes;  average  depth,  102  ft.;  spacing  20  ft.  X  22  ft.  Charge, 
2040  Ib.  of  60  per  cent,  gelatin  and  4475  Ib.  of  40  per  cent,  gelatin. 
Produced  about  40,000  tons  of  stone,  or  6  tons  per  pound. 

A  very  successful  blast,  made  in  a  West  Viriginia  ballast 
quarry,  consisted  of  twenty-four  5^  in.  well-drill  holes  varying 
in  depth  from  56  to  121  ft.  Also  about  the  center  of  the  face 
at  the  bottom  were  drilled  thirty-four  16  ft.  snake  holes,  which 
were  loaded  and  fired  with  the  main  shot.  The  snake  holes 
were  drilled  to  relieve  a  heavy  toe  at  that  point.  Well  holes 
were  spaced  16  to  17  ft.  apart  and  had  an  average  burden  of 
22  ft.;  R.  C.  gelatin  60  per  cent,  and  R.  C.  Extra  33  per  cent. 
dynamite  were  used;  of  the  former  7900  Ib.  was  used  in  the  bot- 
toms of  the  well-drill  holes,  and  of  the  latter  7300  Ib.  in  the  tops 
plus  300  Ib.  in  the  snake  holes.  Nearly  all  holes  were  double- 
loaded,  usually  with  a  12  foot  break.  Cordeau-Bickford  was 
used  in  each  hole  to  detonate  the  explosive.  There  were  64,000 
tons  of  stone  shot  down,  or  4.1  tons  per  Ib.  The  stone  was  well 
broken  and  distributed. 

A  blast  made  in  a  West  Viriginia  quarry,  stone  used  for  ballast, 
consisted  of  seven  holes;  average  depth,  60  ft.;  spacing  18  ft.  X 
20  ft.;  charge,  1600  Ib.  of  50  per  cent,  gelatin  and  1200  Ib.  of 
33  per  cent,  ammonia  dynamite.  Produced  13,000  tons  of  stone 
or  4.6  tons  per  pound. 

Blasting  in  a  cement  quarry  in  New  York  had  been  done,  with 
tripod  drills  putting  down  lj^  in.  holes,  6  ft.  back  from  face, 
6  ft.  apart  arid  12  ft.  deep.  This  method  was  replaced  by  6  in. 
well-drill  holes,  20  ft.  back,  20  ft.  apart  and  65  ft.  deep.  Charge 
is  500  Ibs.  of  40  per  cent.  R.  C.  dynamite  per  hole,  and  holes 
are  shot  in  series  of  from  four  to  twelve.  Explosive  consumption 
per  ton  and  fragmentation  of  product  same  in  both  methods, 
but  other  economies  derived  by  churn  drills  make  the  system 
decidedly  preferable. 

In  a  good  many  instances  it  has  been  observed  that  powder 
consumption  per  ton  of  rock  has  been  about  the  same  whether 
tripod  or  well  drill  holes  were  employed. 


148 


STEAM  SHOVEL  MINING 


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DRILLING  AND  BLASTING 


149 


A  blast  in  a  Texas  limestone  quarry  consisted  in  putting  down 
twenty-four  6  in.  holes,  spaced  10  ft.  apart  and  20  ft.  back  from 
the  face;  depth  varied  from  45  to  70  ft.,  all  run  5  ft.  below  grade. 
Charge,  6000  Ib.  of  40  per  cent,  dynamite  averaging  250  Ib. 
per  hole,  though  some  holes  were  loaded  heavier  than  others 
depending  on  their  burdens.  The  shot  was  very  satisfactory 
although  the  holes  were  spaced  closer  together  than  was  neces- 
sary. One  successful  blast  was  made  with  9  holes,  50  ft.  deep, 
loaded  with  5150  Ib.  of  quarrymen's  special  5  per  cent,  powder. 
Later  work  showed  that  from  7J^  to  10  cu.  yd.  of  rock  were 
thrown  down  per  foot  of  hole  drilled.  The  explosive  cost 
varied  from  9  to  7  cents  per  ton  depending  on  character  of  rock 
and  height  of  face. 

The  foregoing  blasts  will  serve  to  give  a  general  idea  of  what 
should  be  expected  in  well-drill  work. 

Spacing  of  Holes. — Regarding  the  spacing  of  holes,  Table  15 
is  here  reproduced  from  Russell.  Table  16,  from  the  same 
authority,  gives  the  number  of  pounds  of  various  explosives 
which  can  be  loaded  per  foot  in  holes  of  different  diameters, 
if  the  cartridges  are  slit  and  well  tamped. 

TABLE  16. — EXPLOSIVE  CHARGES  IN  POUNDS  PER  FOOT 
OF  HOLES  OP  DIFFERENT  DIAMETERS 


Dia.  of  hole  in 
inches 

I 

1 

OS 

a 

•JJ 

Ki 

S  _ 

£  >> 
OQQ 

(-C     >> 

1 

If 

jS 

1 
3£ 
|| 

3 

4.25 

3.75 

3.68 

3.60 

3.72 

3.25 

3.25 

3.00 

33-2 

5.68 

5.10 

5.0 

4.89 

5.07 

4.42 

4.42 

4.08 

4 

7.55 

6.60 

6.53 

6.33 

6.62 

5.72 

5.72 

5.28 

4V* 

9.35 

8.40 

8.38 

8.06 

8.38 

7.28 

7.28 

6.7 

5 

11.80 

10.50 

10:2 

10.08 

10.35 

9.10 

9.10 

8.42 

5% 

14.94 

13.2 

12.8 

12.53 

13.0 

11.3 

11.3 

10.40 

6 

17.0 

15.0 

14.7 

14.4 

14.9 

13.0 

13.0 

12.04 

6)i 

19.5 

17.5 

17.25 

16.8 

17.49 

15.2 

15.2 

14.0 

7 

23.1 

20.4 

20.0 

19.6 

20.28 

17.7 

17.7 

16.3 

8 

30.2 

26.7 

26.13 

25.6 

26.49 

23.1 

23.1 

21.4 

Proper  spacing  of  holes  depends  on  the  character  of  the 
material  and  the  depth  of  the  face.  It  is  not  subject  to  arbi- 
trary ruling.  A  nice  spacing  for  holes  35  ft.  deep  is  about  12  ft. 


150  STEAM  SHOVEL  MINING 

apart  and  15  ft.  back.  Holes  60  ft.  deep  can  be  spaced  16  ft. 
apart  by  20  ft.  back,  and- holes  100  ft.  or  more  deep,  20  ft. 
apart  and  25  ft.  back  in  most  rocks.  It  is  rarely  advisable  to 
space  more  than  20  ft.  apart  and  in  hard  rocks  it  is  best  to  be- 
gin with  rather  closer  spacing,  say  15  ft.  X  15  ft.  and  work  up. 

Holes  should  be  drilled  3  or  4  ft.  below  the  quarry  floor,  unless 
there  is  a  natural  parting  at  that  level,  in  which  case,  if  holes 
are  sunk  to  grade,  the  bottoms  will  come  clean. 

Systems  of  Shooting. — As  a  usual  practice  well-drill  holes  are 
put  down  in  one  line  more  or  less  equidistant  from  the  face. 
These  are  shot  and  the  material  is  removed  before  the  next 
line  is  shot.  Occasionally,  in  very  hard  rock,  better  results  have 
been  obtained  by  staggering  the  holes.  Another  method  of 
drilling  and  blasting  is  known  as  shooting  against  the  bank, 
or  " buffer"  or  " blanket"  shooting.  By  this  method  a  line  of 
holes  is  shot  down,  the  broken  material  is  not  moved  but  another 
line  of  holes  back  of  the  first  line  is  shot.  The  debris  from  the 
first  shot  thus  blankets  the  second  shot.  It  is  well  adapted 
to  limestone  formations  in  which  the  stone  is  flat,  thinly  lamin- 
ated or  disintegrated  on  top,  and  where  the  face  is  not  over  40 
ft.  high.  The  method  eliminates  the  necessity  of  moving  the 
shovel  as  often  as  when  clear  bank  method  is  used.  Care  must 
be  taken  not  to  load  too  high  in  this  method,  as  often  the  break- 
back makes  it  difficult  to  drill  the  next  line  of  holes. 

In  bench  mining  as  carried  out  by  some  of  the  porphyry  copper 
mines,  it  has  been  the  practice  to  do  the  drilling  and  blasting 
of  the  bank  in  front  of  the  shovel.  On  account  of  narrowness 
of  the  benches  it  has  not  generally  been  possible  to  carry  out  the 
blasting  operations  very  far  in  advance  of  the  shovel  require- 
ments. Great  delays  to  shovel  operation  have  often  resulted 
from  this  practice,  viz.,  the  shooting  of  but  one  hole  at  a  time  in 
front  of  the  shovel.  These  delays  have  been  due  to  unfinished 
holes,  to  moving  the  shovel  back  while  the  bank  is  shot,  to  clean- 
ing off  the  track  after  the  shot  and  to  breaking  up  large  boulders. 

If  the  benches  are  widened  out  by  an  additional  50  ft.,  more 
money  will,  of  course,  be  tied  up  in  advanced  stripping,  but 
great  advantages  in  blasting  will  result  for  a  system  may  be 
used  whereby  several  holes  will  be  shot  at  a  time  well  back  of 
the  shovels.  The  apparent  advantages  of  this  system  are: 

1.  The  shovel  will  not  have  to  wait  for  a  hole  to  be  shot  but 
will  have  broken  ground  ahead  of  it  at  all  times. 


DRILLING  AND  BLASTING  151 

2.  The  shovel  will  not  have  to  move  back  for  the  blast. 

3.  The  loading  track,  on  the  bench  being  blasted,  will  be  the 
width  of  the  shovel  cut  away  from  the  toe  of  the  bank  at  the  time 
of  blasting,  and  will  not  be  covered  with  rock.     After  the  blast 
it  can  be  thrown  into  the  broken  material  and  made  ready  for 
the  next  cut. 

4.  A  big  proportion  of  the  oversize  boulders  can  be  broken 
in  the  most  convenient  and  efficient  way  before  the  shovel 
reaches  them,  as  there  will  be  ample  time.     Further,  blasting 
them  will  not  jar  up  the  shovel  as  is  sometimes  the  case  with 
close  heavy  doby  shots. 

5.  It  is  believed  that  shooting  holes  in  series  will  show  some 
economy    in    explosives.     Certainly    some    economy    could    be 
effected  in  shooting  the  boulders  by  block-holing. 

6.  The  loading  of  the  holes  may  be  done  in  a  quiet  systematic 
way,    without   any   rush   because   of   a   waiting   shovel.     The 
sparks  from  the  shovel  will  not  endanger  the  lives  of  the  powder- 
men.     The  work  may  also  be  cheaper. 

7.  A  more  systematic  method  of  drilling  can  be  used  and  at 
less  cost  per  foot  of  hole. 

With  further  reference  to  point  5,  there  is  a  difference  of 
opinion,  perhaps  based  largely  on  local  conditions  of  the  work, 
but  the  following  questions  have  often  been  put: 

(a)  How  does  the  powder  consumption  per  cubic  yard  com- 
pare, using  single-hole  vs.  multiple-hole  shots? 

(6)  Which  method  leaves  the  broken  ground  in  the  best  con- 
dition for  handling? 

(c)  How  does  the  cost  of  drilling  compare  in  the  two  cases? 

(d)  Is  the  blasted  bank  left  in  better  or  safer  condition  in 
the  one  case  than  the  other?     This  refers  to  large  blocks  which 
may  roll  down  the  bank  endangering  workmen  or  the  shovel, 
and  to  the  partly  blasted  portions  of  banks  which  may  cause 
some  trouble  when  removed  by  the  shovel  or  when  the  next  set 
of  holes  is  drilled  in  portions  so  affected. 

(e)  How  does  the  daily  shovel  output  compare  in  the  two  cases? 
This  assumes  that  the  capacity  of  the  shovel  varies  inversely 
as  the  delays.     Thus  if  delays  due  to  blasting  amounted  to 
6  per  cent,  of  the  total  operating  time,  the  shovel  output  could 
be  expected  to  be  increased  by  roughly  this  amount  if  these 
delays  were  entirely  eliminated,  and  the  cost  per  cubic  yard  of 
handling  material  would  be  reduced  by  a  smaller  amount. 


152 


STEAM  SHOVEL  MINING 


In  some  of  the  examples  of  mining  operations  given  above  these 
questions  have  been  answered  but  not  always  in  the  same  way. 
They  must  be  decided  on  each  individual  job. 

It  is  not  usually  desirable  to  break  ground  too  far  in  advance 
of  shovel  operations,  for,  in  addition  to  the  premature  expendi- 
ture of  the  cost,  heavy  rains  may  so  settle  the  material  that  it 
is  hard  to  handle,  and  in  freezing  weather  the  broken  material 
may  freeze  together  so  firmly  that  reblasting  may  be  necessary. 
Judgment  must  be  used  in  determining  how  far  ahead  blasting 
should  be  carried. 

Breaking  Oversize  Material. — In  so  far  as  economy  of  powder  is 
concerned  in  breaking  oversize  there  is  no  doubt  but  that  block- 
holing  is  by  far  the  best  method.  Elaborate  tests  were  carried 
put  by  the  United  States  Bureau  of  Mines  to  determine  con- 
clusively the  comparative  energy  utilized  by  exploding  powder 
under  water  and  in  the  air.  In  a  few  words  these  tests  showed 
that  much  greater  breaking  effect  was  obtained  with  one-half  the 
powder  by  block-holing  than  by  the  best  mud-capping.  In 
some  cases,  where  80  per  cent,  of  the  total  powder  is  used  for 
bank  shots  and  20  per  cent,  for  breaking  oversize  by  mud- 
capping,  it  may  be  well  worth  while  to  consider  block-holing. 

Table  17  shows  the  actual  saving  in  powder  that  can  be 
effected  with  block-holing  over  mud-capping  and  snake-holing. 

TABLE  17 


Weight  of 
boulder,   pounds 

Size 
cu.  yds. 

Approximate  number  of  l^in.  X  8  in  cartridges  required. 

Mud-capping 

Snake-holing 

Block-holing 

100 

.02 

0.5 

0.5 

0.25 

500 

.12 

1.5 

1.0 

0.25 

1,000 

.23 

2.0 

1.5 

0.50 

2,000 

.47 

3.0 

2.5 

0.67 

3,000 

.70 

3.5 

3.0 

1.00 

4,000 

.93 

4.0 

3.5 

1.25 

5,000 

1.16 

4.5 

4.0 

1.75 

7,500 

1.74 

6.0 

5.0 

2.50 

10,000 

2.33 

8.0 

6.0 

3.50 

Various  Explosives  Used. — There  are  many  explosives  manu- 
factured, nearly  all  of  which  differ  in  some  way;  some  are  slow, 
others  quick,  some  dense,  others  bulky,  some  good  only  in  dry 
work,  others  in  wet  work,  and  some  in  very  cold  weather.  To 


DRILLING  AND  BLASTING  153 

determine  the  best  explosive  for  a  certain  set  of  conditions 
usually  requires  individual  experimenting. 

After  deciding  what  explosives  are  best  suited  to  a  job,  it  is 
advisable  to  standardize  these.  Too  many  varieties  are  likely 
to  be  inconvenient  to  carry  or  confusing  to  work  with. 

In  mining  work  the  explosives  generally  used  are  gelatin 
dynamites,  straight  dynamites,  extra  or  ammonia  dynamites, 
Judson  powder,  nitro-starch  powders,  and  diminishingly,  black 
blasting  powder.  The  straight  nitro-glycerine  dynamites  are 
quietest  and  most  shattering,  also  the  most  sensitive  arid  dan- 
gerous to  handle.  Blasting  gelatin,  containing  about  93  per 
cent,  nitro-glycerine  and  7  per  cent,  gun  cotton  is  the  most 
concentrated  and  powerful.  The  so-called  gelignites  and  gelatin 
dynamites,  varying  in  strength  from  30  to  75  per  cent,  rating, 
are  coming  into  wider  use.  These  and  blasting  gelatin  arte 
comparatively  safe  to  handle  and  are  well  adapted  for  very  wet 
work.  It  is  considered  best  to  detonate  them  with  a  straight 
nitro-glycerine  primer  or  Cordeau.  The  strongest  detonating 
caps  should  be  used. 

The  ammonia  dynamites  and  nitro-starch  explosivas  are  slower 
than  the  straight  dynamites  and  are  not  well  adapted  to  wet 
conditions  where  the  powder  is  to  be  exposed  to  water  for 
a  considerable  time  before  shooting.  They  are  less  sensitive, 
however,  and  well  suited  where  great  shattering  effect  is  not 
desired. 

Judson  powders  and  blas'ting  powders  are  unsuited  for  hard 
rock  excavation  or  wet  work.  They  are  all  right  where  a  slow 
heaving  action  is  desired,  as  in  earth,  shale,  sand  and  laminated 
material.  When  used  in  chambered  holes  in  hard  rock  a  large 
amount  of  oversize  boulders  result. 

The  more  recent  low  freezing  nitro-glycerine  and  gelatin  dyna- 
mites do  not  differ  in  action  from  the  high  freezing  powders  and 
are  just  as  efficient.  Ordinary  dynamite  freezes  at  about  46°F. 
and  must  be  thawed  with  care  in  cold  weather. 

Mr.  Russsll  does  not  recommend  springing  well  drill  holes  in 
quarry  work,  finding  it  a  slow,  tedious,  expensive  and  somewhat 
dangerous  operation,  and  prefers  reducing  the  spacing  of  the 
holes  and  using  a  more  concentrated  powder  to  bring  down  the 
rock. 

Calculation  of  Charges. — No  rule  can  be  given  as  to  the  amount 
of  powder  to  load  in  holes  of  given  depth  as  much  depends  on 


154  STEAM  SHOVEL  MINING 

local  conditions.  It  is  very  important  to  select  the  proper  ex- 
plosive and  then  it  is  necessary  to  "cut  and  try." 

Before  loading  it  is  usual  to  calculate  the  number  of  tons  or 
cubic  yards  available  in  the  blast,  and  then  to  get  about  5  tons 
of  rock  per  pound  of  explosive,  varying  the  load  per  hole  ac- 
cording to  the  burden  or  local  conditions.  (As  a  general  rule 
some  hold  that  a  hole  of  any  depth  should  be  filled  at  least  half 
its  length  with  explosive,  e.g.  a  40  ft.  hole  should  have  20  ft.,  or 
a  60  ft.  hole  30  ft.  of  explosive. 

To  obtain  maximum  breakage  and  proper  distribution  of  the 
explosive  in  the  hole,  the  charge  should  come  up  in  the  hole  to 
at  least  30  ft.  from  the  top,  no  matter  how  deep  the  hole  may  be. 

One  group  of  powdermen  made  up  a  formula  for  charging 
holes  as  follows: 


P  =  pounds  of  powder  to  use  (40  per  cent  Hercules) 
A  =  distance  from  charge  to  toe  (feet) 
H  =  height  of  bank  (feet). 

Allowances  were  then  made  for  any  unusual  conditions  of  burden 
or  material. 

All  such  rules  must  be  considered  as  arbitrary  and  local,  but 
they  may  be  of  some  help  in  starting  operations. 

In  deep  holes  considerable  saving  can  be  made  and  equally 
good  results  obtained  by  breaking  the  load  two  or  three  times. 
The  object  in  breaking  the  load,  besides  saving  explosive,  is  to 
distribute  the  charge  where  the  rock  is  hardest,  skipping  seams 
and  weak  points  where  it  is  not  needed.  In  shooting  a  series  of 
holes  it  is  held  best  to  arrange  the  breaks  so  that  they  are  not 
all  on  the  same  level.  This  amounts  to  the  same  thing  as  shoot- 
ing two  or  more  benches  simultaneously.  In  loading  deep  holes 
the  paper  need  not  be  removed  as  loose  powder  will  be  scattered 
along  the  walls  of  the  hole  and  at  the  mouth.  The  sleeve  used 
at  Nevada  Con.  is  to  be  recommended  for  loading  powder  in 
any  condition. 

In  hard  rocks  a  combination  of  60  per  cent,  and  40  per  cent. 
dynamite  is  recommended.  A  little  60  per  cent,  should  be 
loaded  in  the  bottom  of  each  hole  and  40  per  cent,  used  on  top. 
In  softer  rocks  40  per  cent,  will  usually  be  found  strong  enough 
and  often  a  lower  grade  can  be  used  on  top. 


DRILLING  AND  BLASTING  155 

Detonators. — If  holes  are  double  or  triple  loaded  at  least  two 
electric  exploders  should  be  used  in  each  charge  unit  to  assure 
thorough  detonation  and  to  afford  a  way  out  in  case  one  should 
be  damaged  in  tamping.  Electric  exploders  with  duplex  wire 
leads  have  been  found  a  convenience  in  deep  holes  because  of 
their  handiness  and  strength.  Sometimes  short-length  electric 
exploders  are  used  with  connecting  wire  splices,  if  so  the  splices 
should  be  carefully  made  and  well  taped.  On  one  operation, 
wires  with  red  and  blue  colored  insulation  are  used.  In  multiple 
shots,  either  parallel  or  series,  there  is  thus  less  chance  of 
mistake  in  final  connections. 

Strong  detonators  are  recornmended, .  at  least  No.  6  and  pre- 
ferably No.  8.  In  all  holes  at  least  two  detonators  should  be 
used.  A  good  rule  is  to  place  a  detonator  every  25  ft.  in  the 
explosive  charge.  Electric  exploders  should  be  tested  with  a 
reliable  galvanometer  before  placing  in  the  hole  and  again 
after  the  hole  has  been  loaded  and  tamped.  The  entire  circuit 
should  be  tested  when  all  loading  is  completed  and  all  con- 
nections have  been  made  except  to  the  blasting  machine  or 
power  circuit.  Connections  should  be  made  only  in  series  if  a 
blasting  machine  is  used  and  tests  should  be  made  to  see  that 
the  resistance  of  the  circuit  does  not  exceed  the  capacity  of  the 
blasting  machine.  If  a  power  circuit  is  used  for  firing,  either 
series,  series-parallel  or  parallel  connections  may  be  made.  If 
connections  are  made  in  parallel,  at  least  J£  ampere  per  exploder 
should  be  provided.  If  in  series  or  series-parallel,  2  amperes 
should  be  allowed  for  each  series. 

A  detonator  of  great  merit  in  certain  classes  of  work  is  Cordeau 
or  Cordeau-Bickford  detonating  fusej  This  consists  of  a  lead 
tube  0.22  in.  in  diameter  filled  with  a  high  explosive  compound 
which  is  .perfectly  safe  to  handle  or  knock  about  and  can  only 
be  detonated  by  direct  contact  with  a  blasting  cap.  It  comes  in 
spools  of  150  to  500  ft.  and  is  used  as  follows:  the  end  of  the 
Cordeau  is  laced  through  a  dynamite  cartridge,  which  is  lowered 
to  the  bottom  of  the  hole,  allowing  the  Cordeau  to  extend  the 
full  length  of  the  hole.  The  hole  is  then  charged  in  the  usual 
manner  and  the  Cordeau  is  cut  allowing  about  a  foot  to  extend 
above  the  collar  of  the  hole.  After  the  series  of  holes  to  be  shot 
are  loaded  in  this  way,  the  projecting  ends  of  Cordeau  are  split 
down  about  3  inches  and  forked  Another  length  of  Cordeau 
is  laid  across  these  forked  ends,  which  are  twisted  tightly  around 


156  STEAM  SHOVEL  MINING 

it,  and  all  are  thus  connected  up.  A  blasting  cap  is  attached  to 
the  end  of  the  connecting  Cordeau  by  means  of  a  brass  union  and 
when  this  is  exploded  the  entire  line  of  Cordeau  is  detonated. 
It  thus  causes  a  thorough  detonation  the  whole  length  of  each 
explosive  charge  simultaneously;  any  number  of  holes  can  be 
connected  with  certainty  of  firing. 

Tamping. — A  few  comments  may  be  made  upon  the  tamping  of 
powder  in  the  holes.  In  most  metal  mining  work  this  is  not  done, 
except  as  the  powder  tamps  itself  in  falling  or  as  aided  by  a 
sounder.  The  dirt  shovelled  in  on  top  of  the  charge  is  seldom 
tamped.  A  certain  amount  of  water  is  often  used,  especially 
in  springing,  as  tamping.  Results  thus  obtained  have  generally 
been  satisfactory  but  if  it  is  found  convenient  to  tamp  the  charge, 
the  additional  confinement,  especially  in  unsprung  holes,  may 
show  better  results. 

If  tamping  is  done  the  tamping  block  should  be  of  wood  about 
4  to  5  ft.  long  and  just  easily  clear  the  hole,  say,  5^  in.  diam. 
for  a  6  in.  hole.  It  may  be  given  more  weight  by  babbitting  the 
end.  This  block  will  be  attached  to  a  rope  so  that  it  hangs 
straight  in  the  hole,  and  it  can  then  be  jigged  up  and  down 
directly  by  one  or  two  men,  or  a  light  tripod  and  sheave  may  be 
set  directly  over  the  hole  if  it  is  very  deep.  From  10  to  25  Ib. 
of  powder  may  be  dropped  in  the  hole  at  a  time  and  then  tamped. 
Tamping  should  never  be  done  with  the  drill  stem  by  screwing  a 
wooden  block  in  the  end,  nor  should  any  metal  parts  (except  the 
babbitt)  be  used  on  the  tamping  rig  in  the  hole.  Such  practice 
has  caused  many  accidents. 

Whether  the  powder  is  tamped  or  not,  the  remainder  of  the 
barrel  of  the  hole  should  always  be  carefully  filled  to  the  top  with 
sand,  clay  or  screenings,  and  especial  care  should  be  taken  not  to 
injure  the  exploder  wires  or  Cordeau. 

Safety  Rules. — In  loading  holes  a  few  rules  should  always  be 
kept  in  mind  and  enforced.  Many  of  these,  of  course,  apply 
to  any  kind  of  blasting. 

1.  Permit  no  smoking  in  the  vicinity  of  loading. 

2.  Be  certain  that  a  sprung  hole  is  cool  before  re-springing  or 
loading  it. 

3.  Guard  against  sparks  from  steam  shovels,  locomotives  or 
other  drills  falling  near  the  loading  operations. 

4.  See  that  the  men  assisting  in  the  work^have  no  friction 
matches  in  their  clothing. 


DRILLING  AND  BLASTING  157 

5.  Do  not  allow  loose  powder  to  collect  around  the  mouth  of 
the  hole. 

6.  Do  not  have  more  than  sufficient  powder  to  charge  one  hole 
in  any  one  pile  and  keep  this  carefully  covered  with  a  tarpaulin 
until  time  to  commence  loading.     If  the  hole  is  to  be  sprung  the 
pile  should  be  at  a  reasonably  safe  distance  from  it.     It  is  best 
not  to  have  the  piles  out  over  night. 

7.  If  possible,  complete  the  loading  and  firing  without  inter- 
ruption.    All  the  loading  and  shooting  should  be  done  on  the 
day  shift  if  possible  and  the  powder  crews  should  not  work  over 
eight  hours  except  when  unavoidable  to  finish  a  blast. 

8.  Do  not  connect  up  any  lead  wires  until  just  before  firing. 
Wires  to  be  left  for  any  length  of  time  should  have  the  ends  bur- 
ied in  the  earth.     Electric  storms  have  been  suspected  of  set- 
ting off  blasts. 

9.  Be  sure  dynamite  is  properly  thawed  before  using.     Do  not 
cut,  break  or  try  to  load  frozen  dynamite  in  a  bore  hole. 

10.  Be  sure  that  all  signals  between  blasting  crew  and  other 
pit  crews  are  well  understood  and  obeyed  by  all.     A  sufficient 
time  interval  to  protect  crews  and  equipment  should  be  provided 
for  by  these  signals. 

Gopher  Holes1. — This  method  may  be  called  snake-holing  on 
a  big  scale.  It  is  often  used  in  high  cliff  quarry  work  where  the 
strata  are  irregular,  or  where  drilling  is  inaccessible  or  incon- 
venient. This  is  a  very  old  method  of  blasting  developed  in 
Europe  and  used  to  some  extent  in  the  western  coal  states  and 
in  the  copper  mines.  One  method  is  to  drive  a  tunnel,  say,  4ft. 
X  4  ft.  in  section,  with  jackhammer  drills,  from  40  to  50  ft.  back 
from  the  bottom  or  toe  of  the  face,  and  then  to  drive  cross- 
headings  Tee  fashion  from  this  of  varying  length  according  to 
the  burden  to  be  shifted.  No  explosives  are  placed  in  the  main 
entrance  legs  but  only  in  the  cross-headings.  The  explosives 
may  be  loaded  in  recesses  or  sumps  cut  at  certain  intervals  in 
the  cross  headings,  but  loading  at  grade  gives  good  results.  ., 

If  the  face  is  very  high,  and  it  is  possible  to  do  so  it  is  a  good 
plan  to  sink  well-drill  holes  on  the  surface  from  near  the  outer 
edge  of  the  bench  above,  and  load  lightly  with  explosives.  This 
greatly  assists  in  breaking  up  the  top  ledges  and  gives  the  bank 
a  safe  slope.  It  is  recommended  that  these  holes  extend  about 
one-third  the  way  down.  A  maximum  height  of  about  150 

1S.  R.  Russell,  DuPont  Magazine,  Sept..  1916. 


.158  STEAM  SHOVEL  MINING 

ft.  to  175  ft.  is  all  that  should  be  expected  with  one  system  of 
adits,  but  cases  where  the  bank  was  240  ft.  high  have  been  suc- 
cessfully blasted.  The  method  is  not  economical  if  the  face  is 
less  than  70  or  80  ft. 

The  explosives  generally  used  in  gopher-holes  are,  say,  twenty 
per  cent,  of  40  per  cent,  to  60  per  cent,  dynamite  and  eighty 
per  cent,  of  DuPont  R.R.P.  or  black  powder.  The  explosive 
charges  are  placed  15  to  20  ft.  apart  and,  in  loading,  it  is  best  to 
remove  the  cartridges  from  the  boxes  so  that  they  can  be  packed 
in  better.  Dynamite  is  laid  on  the  bottom  and  R.R.P.  on  top. 

A  unit  charge  may  consist  of  a  few  hundred  up  to  several 
thousand  pounds,  depending  on  the  burden.  From  two  to  three 
electric  detonators  should  be  primed  in  each  unit.  As  a  safety 
precaution  against  misfires,  a  line  of  Cordeau  should  be  strung 
all  along  the  adit  and  drifts  connecting  all  explosive  units. 

For  tamping  between  the  units,  screenings  from  the  spoil 
of  driving  may  be  used.  At  the  intersection  of  the  legs  and  at 
least  half  way  out  the  main  leg,  lean  concrete  should  be  used 
for  tamping.  This  should  be  allowed  to  set  about  48  hours 
before  the  blast  is  fired. 

There  are  several  methods  of  carrying  the  wires  and  making  the 
connections.  The  wires  may  be  put  through  pipes  or  grooved 
boards,  but  it  is  recommended  that  they  be  strung  through  eye 
bolts  driven  in  the  roof.  A  separate  pair  of  wires  should  run 
from  the  portal  to  each  unit;  No.  14  gauge  or  heavier  copper 
wire  should  be  used  Each  pair  of  wires  should  be  carefully 
tagged  to  indicate  the  unit  it  leads  to.  Tests  should  be  made 
progressively  to  insure  that  the  circuit  is  intact.  When  a  power 
circuit  is  available  parallel  connections  should  be  made. 

Very  good  fragmentation  is  obtained  by  this  method  of  blast- 
ing and  under  certain  conditions  it  is  the  most  economical  method 
to  employ.  From  five  to  six  tons  of  material  can  be  obtained 
per  pound  of  explosive.  While  this  method  is  applicable  to  many 
operations,  yet  if  the  face  can  be  economically  drilled  it  is  advisable 
to  recommend  it. 

At  the  mines  of  the  Utah  Copper  Company,  the  great  240-ft. 
bank  was  blasted  by  gophering  and  well-drilling  combined.  Fig. 
33  illustrates  the  method  and  details  of  the  work  and  shows  the 
powder  charges  employed. 

Gopher-holing,  when  first  used  on  the  Mesabi  iron  range,  con- 
sisted in  making  the  holes  large  enough  to  permit  a  man  to  enter 


DRILLING  AND  BLASTING  159 

and  work,  but  frequent  accidents  caused  this  system  to  be  aban- 
doned, and  gopher  holes  now  have  an  average  diameter  of  about 
15  in. 

The  benches  are  drilled  and  blasted  by  regular  crews  of 
"  gopher-holers  "  made  up  of  10  to  30  laborers,  working  in  groups 
of  two  men.  The  benches  are  15  to  25  ft.  high  and  are  riddled 
with  a  series  of  holes  15  to  25  ft.  deep,  spaced  15  to  25  ft.  apart. 
The  general  rule  is  to  make  the  horizontal  distance  between  the 
centre  of  the  loading  track  and  the  chamber  of  the  gopher  hole 
5  or  6  ft.  less  than  the  reach  of  the  shovel.  The  collar  of  the 


k ' "    p  "X  t     (  e  "Keystone  Holes  Sprung 
•<\    25'  I   25'  I   aPjRJ  and  Loaded  with  50  Ib. 
:       to'**'i-o  Tfo"       \WPerCentfodHPowder 

30'      30'/     30'         \and7-tvlOCansBfackPowder 
\ 


\: 


(Keystone Holes  B/asted off erwarofs 
\\  if  necessary,  fo  Break  upper  Portion, 
J  and  get  Bank  bach  to  about  an 
\Average  Safe  Slope 


"::;•.         1 120  Cans  of  Black  Powder 
fa  V...  J  each  Primer  of  500  Ib.  60 
L         \PerCentfodHPowder 

All  Three  Shot  Simultaneously 


FIG.  33. — Drilling  and  blasting  240-ft.  bank;  gophering. 

hole  is  at  the  base  of  the  bank  and  the  hole  points  downward 
at  an  angle  of  from  10°  to  20°  from  the  horizontal.  The  spacing 
of  the  holes  depends  on  the  hardness  of  the  material  and  the  bur- 
den imposed.  The  holes  are  made  with  a  long  spoon  shovel, 
made  by  slightly  turning  up  the  edges  of  the  blade  of  a  No.  2 
round-pointed  shovel  and  fitting  to  it  a  25  ft.  handle  of  2  or 
3  in.  diameter.  When  a  hard  seam  is  encountered  it  is  drilled 
with  a  24  ft.  augur,  or  a  moil,  and  is  sprung  by  pushing  in  one  or 
two  sticks  of  powder  with  a  pointed  loading  stick,  and  then  firing 
with  a  blasting  machine.  The  loose  ground  is  then  removed  with 


160  STEAM  SHOVEL  MINING 

the  shovel.  If  a  boulder  is  struck  in  the  hole,  repeated  blasting 
with  60  per  cent,  dynamite  will  often  shatter  it  sufficiently  to 
allow  the  hole  to  be  continued.  If  this  is  not  successful,  the 
hole  is  bottomed  against  the  boulder  and  a  new  one  started  a 
few  feet  away.  From  2  to  12  hr.  is  consumed  per  hole  and 
costs  from  $2  to  $8  for  labor. 

In  winter  the  top  of  the  banks  freezes  as  deep  as  8  ft.,  and 
unless  this  crust  is  broken  by  top  drilling  before  gopher-holing  is 
done,  the  latter  usually  undercuts  the  bank,  causing  slabs  of 
frozen  ground  to  slide  down  and  bury  the  loading  track. 

The  powder  boss  determines  the  size  of  the  powder  charge 
from  the  height  of  the  bank  and  the  material  taken  from  the 
hole.  With  a  25-ft.  bank,  15  to  25  sticks  of  dynamite  are  used 
to  spring  the  hole,  which  is  then  loaded  (after  cooling)  with  from 
five  to  ten  25-lb.  kegs  of  DuPont  black  blasting  powder.  The 
powder  is  fed  in  through  a  long  wooden  launder,  about  2  in.  X 
2  in.  inside  cross  section,  fitted  with  a  covered  hopper  at  one  end. 
A  keg  of  powder  is  emptied  into  the  hopper,  the  cover  is  closed 
and  the  loader  is  oscillated  by  a  12-ft.  cross  handle,  causing  the 
powder  to  run  down  the  launder  into  the  chamber  of  the  hole. 
The  long  cross  handle  allows  the  powdermen  to  stand  6  ft.  on 
either  side  of  the  hole  instead  of  in  front  of  it.  The  closed  hopper 
protects  the  powder  from  flying  sparks.  Another  method  is  to 
attach  a  hand  blower  to  the  launder  by  means  of  a  rubber  hose, 
and  as  the  powder  is  blown  in  the  launder  is  gradually  pulled 
out.  Both  methods  are  quite  safe.  Wooden  spoons,  3  in.  X  3 
in.  in  cross  section,  and  2%  ft.  long,  fitted  with  25  ft.  handles, 
have  been  used  but  are  not  as  good. 

The  detonator  consists  of  from  2  to  5  sticks  of  60  per  cent, 
dynamite  with  exploders,  and  is  placed  about  two-thirds  of  the 
way  down  the  charge.  The  two  exploders  may  both  be  electric, 
or  may  be  one  electric  and  one  ordinary  cap  with  fuse.  The 
latter  combination  is  in  more  general  use,  since  tamping  some- 
times injures  the  cap  wires.  Tamping  is  essential,  and  is  done 
by  filling  the  holes  to  the  collar  with  sand  or  gravel.  Holes  are 
fired  in  sets  of  3  to  5  at  a  time. 

^  A  unique  method  of  gopher  blasting  has  been  worked  out  at 
the  mines  of  the  Chile  Copper  Company,  at  Chuquicamata, 
Chile.1  Instead  of  the  entrance  to  the  gopher  drifts  being  from 

1  E.  E.  Barker,  M.  &  S.  P.,  Sept.  30,  1916. 
Howard  W.  Moore,  M.  &  S.  P.,  July  8,  1916. 


DRILLING  AND  BLASTING  161 

the  working  face,  it  is  placed  well  back  of  the  face,  this  being 
accomplished  by  means  of  a  shaft  and  connecting  drift.  Blast- 
ing by  means  of  churn-drilling  was  first  tried  but  the  ground 
proved  quite  hard  and  the  gopher  hole  method  was  adopted. 
The  latter  has  resulted  in  lower  costs  per  cubic  yard  of  material 
blasted  because  less  footage  has  to  be  driven  between  charges, 
and  because  the  expense  of  springing  operations,  used  in  well- 
drill  holes,  is  eliminated.^ 

Some  of  the  details  of  this  work  may  here  be  interesting. 

With  the  method  of  blasting  by  well-drill  holes',  5%  in.  holes 
were  drilled  about  25  ft.  apart,  in  rows  from  40  to  50  ft.  apart, 
and  to  a  depth  of  4  to  5  ft.  below  the  grade  of  the  benches,  which 
were  40  to  100  ft.  high.  These  holes  were  sprung  from  5  to  7 
times  using  60  per  cent,  or  75  per  cent,  dynamite,  and  a  chamber 
6  to  8  ft.  in  diameter  was  formed,  which  was  then  loaded.  This 
loading  was  done  in  a  manner  similar  to  that  used  by  the  Nevada 
Consolidated  Copper  Company. 

The  cost  of  the  drilling  was  unusual,  viz.,  from  $2.50  to  $3.60 
per  foot.  On  this  work  Keystone  electric  drills  made  about 
17  ft.  per  shift  and  Cyclone  electric  drills  made  about  23  ft.  per 
shift.  The  latter  machines  proved  very  satisfactory.  Lower 
footages  were,  of  course,  made  on  deeper  prospect  holes. 

The  method  of  blasting  from  tunnels  is  as  follows:  shafts  are 
sunk  at  several  convenient  parts  of  the  bench  to  a  depth  of  3 
meters  below  grade,  from  the  bottoms  of  these  shafts  cross-cuts 
are  run  parallel  to  the  short  axis  of  the  orebody  and  about  nor- 
mal to  the  bench  face,  and  from  these  cross-cuts,  drifts  are  run 
every  15  to  30  meters,  parallel  to  the  long  axis  of  the  orebody. 
See  Fig.  34.  The  cost  of  this  work  is  about  $10.00  per  ft.  The 
spacing  has  been  increased  to  30  meters,  where  the  banks  are  at 
least  1J£  times  as  high.  In  these  drifts  the  charges  of  explosives 
are  placed  at  10  meter  intervals.  In  calculating  the  loading 
charges,  cross  sections  are  taken  to  scale  through  the  loading 
points  and  normal  to  the  bench  face  as  illustrated  by  Fig.  35. 
Scaling  the  line  of  least  resistance  indicates  the  approximate 
charge  required  and  it  has  been  determined  that  from  463  to 
600  Ib.  of  black  powder,  depending  on  the  material  to  be  blasted, 
should  be  loaded  in  each  charge  for  every  meter  as  measured  on 
the  line  of  least  resistance.  To  translate  the  black  powder,  which 
is  manufactured  in  Chile,  into  40  per  cent,  dynamite  the  result- 

11 


162 


STEAM  SHOVEL  MINING 


ant  charges  may  be  divided  by  the  factor  1.50,  or  into  60  per 
cent,  dynamite  by  the  factor  2.25. 

For  compactness  the  powder  is  loaded  in  sacks  of  100  Ib.  each 
and  these  sacks  are  closely  piled  from  floor  to  roof  of  the  drift, 
the  interstices  between  the  sacks  being  filled  with  sand  or  muck. 
In  the  centre  of  each  charge  are  placed  two  boxes  of  60  per  cent, 
dynamite  which  serve  as  primers.  One  electric  exploder  is  care- 
fully placed  in  each  box  of  dynamite.  See  Fig.  36.  The  lead 
wires  from  the  primers  are  carried  along  the  floor  of  the  drift 
in  grooved  wooden  stringers  (2  in.  X  3  in.  with  %  in.  groove) 
provided  with  J^  in.  covers.  After  a  chamber  is  charged  and 


_  ^-  Shore/  Bench     .-  Broken  (fock,  well  Tamped 
->>^  £; 

' 


Ppwa/er 


'ORE 


~-~  Broken  Rock,         Primers 
:     Well  Tamped        ore  Boxes  of 
60%  Dynamite 


Plan  of  Tunnel  Blasting,  Chuqui'camata, Chile. 
FIG.  34.— Plan  of  tunnel  blasting,  Chuquicamata,  Chile. 

connections  made,  broken  rock  is  used  to  fill  up  the  drift  closely. 
Two  separate  electric  circuits  on  different  transformers  are  pro- 
vided as  a  precaution  against  misfires.  From  careful  experi- 
ments it  was  found  that  for  a  series  of  20  exploders,  0.75  amperes 
current  under  110  volts  e.m.f.,  was  the  least  current  that  would 
explode  the  series.  It  was,  therefore,  determined  never  to  use  a 
safety  factor  of  less  than  4,  or  in  this  case  to  provide  3  amperes. 
Each  exploder  plus  about  30  ft.  of  fuse-wire,  showed  a  resistance 
of  about  2  ohms.  See  Fig.  37. 

After  the  drift  is  loaded,  the  cross-cut  leading  back  to  the  other 
workings  is  filled  with  broken  rock  to  within  4  meters  of  the  first 
drift  back,  and  at  this  location  a  solid  concrete  bulk-head  is  put 
in,  as  illustrated  in  Fig.  34.  The  principal  reason  for  this  is  to 


DRILLING  AND  BLASTING 


163 


keep  the  gases  after  the  shot,  out  of  the  workings  back  of  the 
shot. 

The  handling  of  such  large  quantities  of  explosive  requires 
constant  close  care  and  supervision.  Further  experimental  work 
and  experience  will  be  required  before  the  most  efficient  spacing, 


Use  4>3lb.per  Metre  Measured  on  Line  of  L  east  Resistance  for  Block  Powder 
Use-^-lb.per  Metre  Measured  on  Line  of  Line  of  Least  Resistance  for 60%  Dyr 


Average  Amount  of  Black  Powder  Used'  1. 35 1 b. per  Cu.  Mttre.    [  Plack  Powaler 
One  Cu.  Metre  Rock*  2.83-tons  \ ln  '00 1  b.  Sacks 

Average  Amount  of  Black  Powder  Used  per  Ton*  045 Jb. 

Face  of  dank 

^^..  Line  of  Least  Resistance 
Shovel  Bench 


Primers  60% 
Dynamite 


FIG.  35. — Method  of  calculating 
powder  charge. 


FIG.  36. 


(Wires  Laid 
^jfl^"1'  J//T Grooved 
""\Yfooden6uides 

-Method  of  loading  tunnel 
for  blasting. 


charges  and  other  details  are  finally  determined,  but  the  results 
obtained  to  date  are  considered  very  satisfactory. 

About  \Y±  Ib.  of  black  powder  and  0.02  Ibs  of  40  per  cent, 
dynamite  are  consumed  per  ton  of  material  broken.  About  400 
Ib.  of  powder  is  the  load  per  lineal  foot  of  tunnel  loaded.  More 


All  60%  Dynamite 


I  Transformers,- 1  Kw.  A.  C.,Sinq!e 
Phase -1 10  V. 
Wire  No.  12  or  14  B.&S.  6auqe  Rubber  Insulated. 
Amperage  Required  for  ?0  Caps,=  0.15  Amp. 
Volfs  Required  for  20  Caps,  =  1 10  Volts . 
Ohms  Resistance  of  One  Cap  and^Me+ers  of  Fuse  Wire, =2.00 Ohms 
Cajfts  in  Series  Jyto  Series 

FIG.  37. — Diagram  for  tunnel  blast  wiring. 


recently  the  black  powder  has  been  reduced  to  as  low  as  0.6 
Ib.  per  ton  of  ground  broken. 

Mixtures  of  clay  and  gravel  used  for  ballasting  have  been 
loosened  up  for  handling  with  steam  shovels  by  a  simple  method 
of  gopher-holing.  In  one  case  holes  20  inches  wide  by  26  inches 
high  were  extended  into  the  gravel  bank  a  distance  of  26  feet 


164  STEAM  SHOVEL  MINING 

and  then  turned  at  right  angles  for  10  feet.  The  excavations 
were  made  by  a  man  lying  down  and  working  the  material  loose 
with  a  very  short  handled  pick.  The  charge  of  black  powder  was 
placed  in  the  extreme  end  of  the  10  foot  leg,  the  remaining  dis- 
tance of  which,  and  a  few  feet  at  the  end  of  the  26  foot  drift, 
was  then  refilled  with  gravel.  This  mixture  was  very  compact, 
being  about  75  per  cent,  small  gravel,  20  per  cent,  clay  and  5 
per  cent.  sand.  The  method  of  loosening  was  cheap  as  about 
80  ballast  cars  of  material  were  loosened  per  blast  and  the  com- 
plete drifts  were  dug  at  a  cost  of  about  $18. 

Storing  and  Thawing  Explosives. — All  of  the  important 
powder  manufacturers  issue  detailed  instructions  and  will  plan 
proper  facilities  for  the  storing,  handling  and  thawing  of  ex- 
plosives. It  is  advisable  to  consult  with  their  engineers  in  plan- 
ning this  operation. 

On  the  Mesabi  range,  powder  magazines  of  heavy  sheet  steel 
are  furnished  by  the  powder  company  supplying  the  explosives. 
Sheet  iron  magazines  for  caps  and  fuses  are  usually  built  by 
the  operators.  Thawing  houses  are  built  according  to  recom- 
mendations furnished  by  the  DuPont  Powder  Comapny,  and 
are  5  ft.  X  8  ft.  outside.  Shallow  drawers,  with  1  in.  holes 
perforating  the  bottom,  are  provided  in  which  to  store  the  cart- 
ridges, and  are  accessible  from  the  outside  of  the  building. 
A  radiator  in  the  back  part  of  the  thawing  house  is  supplied  with 
hot  water  through  a  1  in.  pipe  from  a  heater  in  a  separate  build- 
ing. This  heater  is  a  small  water-jacketed  coal-fired  stove. 
The  housing  for  the  heater  is  4  ft.  X  4  ft.  and  is  placed  not  less 
than  10  ft.  from  the  thawing  house. 

At  some  of  the  copper  properties  larger  powder  magazines 
have  been  built  of  heavy  logs,  stone  and  concrete.  If  it  is 
necessary  to  keep  large  stocks  of  explosives  on  hand,  it  is  best 
to  distribute  them  in  several  magazines,  at  a  safe  distance 
apart  and  from  dwellings  or  townsites.  They  should,  however, 
be  quite  accessible  and  open  to  observation  or  protection  in 
times  of  labor  or  other  trouble. 

The  use  of  low  and  extra  low  freezing  powders  has  in  many 
places  relieved  much  of  the  trouble  of  thawing.  The  use  of  the 
refrigerator  type  of  powder  car  for  transporting  thawed  powder 
about  the  pits  has  also  been  found  useful. 

It  is  often  necessary  to  conform  to  state  or  federal  regulations 
regarding  the  storing  and  transportation  of  explosives,  and  such 


DRILLING  AND  BLASTING 


165 


regulations  should  be  carefully  observed.  The  Interstate  Com- 
merce. Commission's  requirements  for  the  storage  of  explosives 
in  magazines  is  quoted  in  the  following  tabulation  from  the 
Annual  Report  of  Chief  Inspector  of  the  "  Bureau  for  the  Safe 
Transportation  of  Explosives  and  other  Dangerous  Articles," 
dated  Feb.  1,  1911  (Tables  revised  Nov.  30,  1912,  to  include 
intermediate  quantities) . 

TABLE  18. — MINIMUM  DISTANCES 


Lbs.  of 
explosives 

Distances, 
inhabited 
building, 
barricaded1 
(feet) 

Distances, 
public 
railway, 
barricaded1 
(feet) 

Lbs. 
of 

explosives 

Distances, 
inhabited 
building,  bar- 
ricaded 

(feet)  i 

Distances, 
public  railway 
barricaded 

(feet)  i 

50 

120 

70 

60,000 

1,565 

940 

100 

180 

110 

65,000 

1,610 

970 

200 

260 

155 

70,000 

1,655 

995 

300 

320 

190 

75,000 

1,695 

1,020 

400 

360 

215 

80,000 

1,730 

1,040 

500 

400 

240 

85,000 

1,760 

1,060 

600 

430 

260 

90,000 

1,790 

1,075 

700 

460 

275 

95,000 

1,815 

1,090 

800 

490 

295 

100,000 

1,835 

1,100 

900 

510 

305 

125,000 

1,900 

1,140 

1,000 

530 

320 

150,000 

1,965 

1,180 

1,500 

600 

360 

175,000 

2,030 

1,220 

2,000 

650 

390 

200,000 

2,095 

1,255 

3,000 

710 

425 

225,000 

2,155 

1,295 

4,000 

750 

450 

250,000 

2,215 

1,330 

5,000 

780 

470 

275,000 

2,275 

,365 

6,000 

805 

485 

300,000 

2,335 

,400 

7,000 

830 

500 

325,000 

2,390 

,435 

8,000 

850 

510 

350,000 

2,445 

,470 

9,000 

870 

520 

375,000 

2,500 

,500 

10,000 

890 

535 

400,000 

2,555 

,535 

15,000 

975 

585 

425,000 

2,605 

,560 

20,000 

1,055 

635 

450,000 

2,655 

,590 

25,000 

1,130 

680 

475,000 

2,705 

,620 

30,000 

1,205 

725 

500,000 

2,755 

,655 

35,000 

,275 

765 

600,000 

2,935 

,760 

40,000 

,340 

805 

700,000 

3,095 

,855 

45,000 

,400 

840 

800,000 

3,235 

1,940 

50,000 

,460 

875 

900,000 

3,355 

2,015 

55,000 

,515 

910 

1,000,000 

3,455 

2,075 

1  "Barricaded,"  as  here  used,  signifies  that  the  building   containing  ex- 
plosives is  screened  from  other  buildings  or  from  railways  by  either  natural 


166  STEAM  SHOVEL  MINING 

Care  in  Use  of  Explosives. — All  operators  know  that  de- 
tailed care  in  the  use  of  explosives  cannot  be  over-emphasized. 
Nevertheless,  many  accidents  occur  each  year  to  which  definite 
simple  causes  can  be  assigned,  and  many  others  occur,  the  cause 
of  which  is  impossible  to  ascertain.  In  recent  years  a  great 
deal  of  interest  has  been  taken  in  safety  work  and  large  sums 
have  been  spent  by  the  big  companies  in  an  endeavor  to  make 
the  operations  as  safe  as  possible.  Safety  regulations  have 
been  issued  by  many  companies,  printed  in  pamphlet  form  and 
in  the  languages  of  all  workmen. 

Special  care  has  been  given  to  the  selection  and  training  of 
powder  foremen,  for  upon  them  rests  the  direct  supervision 
and  common  sense  of  the  work.  Both  foremen  and  men  are 
impressed  with  the  motto  " Safety  First"  and  taught  to  consider 
themselves  individually  a  committee  of  safety.  They  are  in- 
vited at  all  times  to  submit  suggestions  as  to  how  the  operations 
can  be  better  or  more  safely  conducted,  and  from  such  sugges- 
tions many  rules  and  devices  have  been  improved.  In  starting 
a  new  property  experienced  men  should  be  entrusted  with  the 
training  of  the  personnel  required  for  powder  work. 

or  artificial  barriers.  Where  such  barriers  do  not  exist,  the  distances  shown 
should  be  at  least  doubled. 

"An  artificial  barrier  shall  be  held  to  mean  an  artificial  mound  or  properly 
revetted  wall  of  earth  of  a  minimum  thickness  of  not  less  than  three  feet, 
of  such  height  that  any  straight  line  drawn  from  the  top  of  any  side  wall 
of  the  building  containing  explosives  to  any  part  of  the  building  to  be  pro- 
tected will  pass  through  such  intervening  artificial  barrier,  and  any  straight 
line  drawn  from  the  top  of  any  side  wall  of  the  building  containing  explo- 
sives to  any  point  twelve  feet  above  the  center  of  the  railway  will  pass 
through  such  intervening  artificial  barrier.  The  foregoing  definition  as  to 
height  shall  also  apply  to  any  natural  barrier. 

"For  quantities  not  given  in  the  above  table  use  distances  shown  for 
nearest  tabulated  quantity,  or  if  extreme  accuracy  is  desired  take  pro- 
portionate figures." 


CHAPTER  V 

DISPOSAL  OF  MATERIAL 
TRANSPORTATION 

Trackage  Arrangements. — Every  effort  should  be  made  to 
supply  a  proper  balance  of  train  service  to  keep  the  shovels 
operating  as  continuously  as  practicable.  The  efficiency  of 
this  service  will  depend  on  the  amount,  type  and  condition  of 
equipment  available,  length  of  haul,  track  layout,  weather 
conditions  and  good  "railroading." 

Ideal  conditions  would  be  where  the  track  was  so  arranged  . 
that  a  train  of  empties  could  follow  into  loading  position  at 
the  side  of  the  shovel  just  as  a  loaded  train  pulls  out.  In  some 
large  pits  a  ladder  track  layout  is  arranged  where  the  empty 
or  return  track  from  the  yards  branches  into  a  number  of  loading 
tracks  that  feed  the  individual  shovels.  At  the  opposite  end 
of  the  pit  these  tracks  converge  into  a  single  track  connected 
to  the  main  track  out  of  the  pit.  More  commonly  there  is  a 
passing  track  provided  for  each  shovel.  Where  it  is  not  prac- 
ticable to  get  a  passing  track  in,  a  stub  track  or  " lie-by"  may  be 
laid  just  long  enough  to  take  an  empty  train  while  the  loaded 
train  passes  by.  The  trackage  arrangement  must  continually 
be  kept  in  mind  as  it  is  constantly  changing. 

Delays. — Delays  due  to  train  service  vary  widely,  depending 
on  the  layout  and  how  well  the  crews  are  organized.  Delays 
may  be  due  to  blasting,  covered  track,  moving  shovel,  changing 
trains,  spotting  cars,  dumping  or  simply  waiting  for  trains. 
The  nearer  the  shovel  the  empty  train  is  and  the  more  cars  hauled 
per  train,  the  less  time  is  lost  in  changing  trains.  Track  con- 
ditions affect  the  train  length  in  several  ways,  for  example, 
at  the  end  of  a  cut  there  may  be  insufficient  room  ahead  of  the 
shovel  to  accommodate  the  whole  train,  which  then  must  be  cut 
up  and  switched  in  and  out  in  short  units.  When  this  sort  of 
loading  is  required  the  switch  should  be  as  well  up  with  the 

167 


168  STEAM  SHOVEL  MINING 

shovel  as  possible.  The  effect  of  curvature,  grades  and  weather 
on  the  length  of  trains  has  already  been  taken  up  in  Chapter  II. 
The  advantages  of  the  Woodford  centrally  controlled  system 
has  been  fully  described  there. 

Distribution  of  Equipment. — The  transportation  equipment 
for  handling  waste  is  usually  kept  quite  separate  from  that  for 
handling  ore,  and  is  usually  of  a  different  type.  ^  On  the  iron 
ranges  and  at  the  porphyry  copper  mines  the  ore  cars  used  are 
furnished  by  the  railroads.  These  are  brought  to  an  assembly 
yard  and  from  this  yard  pit  engines  draw  on  the  supply  as  re- 
quired. The  pit  engines  haul  the  empties  to  the  loading  posi- 
tions of  shovels  working  in  ore  and  return  with  the  loads  to  the 
assembly  yard  where  the  ore  trains  are  made  up  for  railroad 
transport  to  the  docks  or  mills.  The  stripping  equipment  is 
handled  entirely  by  the  mine's  organization  or  by  the  stripping 
contractor. 

Routing  of  Overburden. — The  waste  haul  depends  on  the 
location  of  the  dumps.  As  a  rule  there  will  be  several  dumps  in 
use,  and  it  is  the  duty  of  the  engineer  to  prepare  a  schedule  of 
waste  routing  which  will  allocate  the  stripping  from  various 
areas  and  elevations  in  the  pit  to  those  dumps  best  suited  to 
take  care  of  the  waste.  Such  a  routing  schedule  should  .be  made 
up  monthly  and  clearly  indicate  what  parts  of  the  pit  it  is  ex- 
pected to  strip,  the  yardage  expected  and  the  dumps  to  which 
each  component  portion  is  to  go,  as  well  as  the  remaining  ca- 
pacity of  each  of  the  dumps.  It  is  also  of  interest  to  know  the 
relative  cost  of  moving  overburden  to  the  different  dumps. 

Distribution  of  Crews. — On  the  Mesabi  Range,  the  overburden 
is  'transported  from  two  to  four  miles.  The  main  haulage 
tracks  are  on  grades  of  from  K  per  cent,  to  2  per  cent,  and  are 
well  kept  up.  Rod  engines  of  from  50  to  60  tons  are  generally 
used,  and  the  dump  cars  range  from  7  to  20  cu.  yds.  capacity. 
The  dump  crews  consist  of  three  gangs.  One  gang  is  on  the 
dump  and  attends  to  the  unloading  of  the  cars  and  cleaning 
the  track;  another  gang  shifts  the  track;  the  third  gang  is  sta- 
tioned at  a  point  where  the  dump's  tracks  converge  on  the 
main  line,  and  here  the  men  right  and  lock  the  cars  in  position 
for  loading. 

At  the  porphyry  copper  mines,  the  one  crew  at  the  point  of 
dumping  usually  takes  care  of  all  of  these  duties.  In  this  way 
all  hands  are  available  for  any  operation  and  very  little  time  is 


DISPOSAL  OF  MATERIAL  169 

lost.  The  train  is  quickly  dumped,  righted  and  locked,  and  the 
track  cleared  to  enable  it  to  return  to  the  pit.  The  dump 
crew  then  devotes  its  time  to  further  clearing  of  track  and  bank, 
or  to  shifting  tracks. 

Use  of  Salt  Solution. — To  assist  dumping  in  freezing  weather, 
when  handling  moist  material,  which  has  a  decided  tendency  to 
build  up  on  car  bottoms,  a  hot  salt  solution  is  recommended 
from  Mesabi  practice^  The  salt  water  tank  is  made  of  wood, 
holds  about  2500  gal.  and  is  filled  with  water  and  salt  to  form  a 
saturated  solution.  This  solution  is  heated  to  the  boiling  point 
by  a  steam  pipe  or  small  vertical  boiler.  In  freezing  weather 
the  car  bottoms  are  periodically  sprinkled  with  this  solution 
from  a  hose.  The  result  is  satisfactory  and  the  expense  not 
great.  The  tank  should  be  conveniently  located  to  prevent 
delays  to  equipment  being  treated. 

Economy  in  Large  Cars. — At  one  of  the  porphyry  copper  mines 
an  attempt  was  made  to  determine  the  relative  economy  of 
loading  20-cu.  yd.  and  18-cu.  yd.  (water  measure)  dump  cars;, 
these  cars  having  a  capacity  of  16.1  and  14.5  place  cu.  yds. 
respectively.  The  advantages  in  hauling,  spotting  and  dump- 
ing the  20-cu.  yd.  cars  seemed  quite  evident,  but  it  was  desired 
to  ascertain  just  what  advantage  was  gained  in  loading  time. 
Under  conditions  as  nearly  alike  as  could  be  found,  covering  a 
period  of  three  months,  and  eliminating  all  time  factors  but  the 
loading  time,  the  results  seemed  to  show  that  there  is  an  ad- 
vantage in  using  larger  cars  and  that  under  similar  conditions 
more  yardage  can  be  loaded  into  large  cars  than  small  ones  in 
the  same  space  of  time. 

Estimating  Cost  to  New  Dump. — When  a  new  dump-site  is 
proposed  it  is  often  desired  to  know  what  the  cost  of  trans- 
portation to  the  new  site  will  be  as  compared  to  that  to  other 
active  dumps.  A  fair  estimate  of  this  may  be  made  by  noting, 
over  a  week's  time,  the  average  number  of  cars  per  locomotive- 
hour  which  are  hauled  to  the  active  dump,  and  by  observing 
the  operations  of  the  trains  and  proportioning  the  time  for  each 
phase  of  the  work.  These  results  can  then  be  used  to  estimate 
the  cubic  yards  per  locomotive-hour  which  could  be  hauled  to 
the  new  dump,  making  allowance  for  difference  in  length  of 
.  haul,  passing  of  trains  or  other  conditions.  The  data  may  be 
set  down  as  follows: 


170  STEAM  SHOVEL  MINING 

ESTIMATED  COST  OF  TRANSPORTATION  TO  DUMP  A. 

Length  of  haul,  round  trip • 9200  feet 

Grades — 1250  feet  4  per  cent,  in  favor  of  loads. 
2600  feet  2  per  cent,  adverse  to  loads. 

Average  number  of  cars  per  train 5  (or  72.5  cu.  yds.) 

Average  number  of  cars  per  locomotive-hour 5 

Overhead  cost  per  locomotive-hour $3 . 00 

(includes  supt.,  foreman,  yardmaster,  laborers,  etc.,  but  not  dump 
gangs.) 

Labor  cost  per  locomotive-hour $1 . 28 

Supplies  cost  per  locomotive  hour  (9/8  labor) 1 . 44 


Total  cost  per  locomotive-hour $5 . 72 

Total  cost  per  cu.  yd $0 . 0789 

DISTRIBUTION  OF  TIME  CONSUMED 

Average  time  per  round  trip  for  five-car  train  equals  60  minutes. 

Minutes 

Loading  train 18 

Time  train  in  motion 15 

Switching 6 

Dumping  cars .5 

Waiting  at  switch  to  meet  other  train 4 

Delays  at  shovel 6 

Other  delays 6 

Total 60 

Average  running  speed  is  9200  -f-  15  =  613  ft.  per  minute. 
It  takes  20  sec.  to  start  or  stop  a  train  and  requires  a  distance  of 
200  ft.  On  this  run  there  are  seven  stops  and  starts  per  round 
trip.  The  speed,  when  underway  may  be  found  as  follows: 

14  X  20  sec.  =  280  sec.  or  say  5  min.  in  starts  and  stops. 

14  X  200  ft.  =  2800  ft.  distance  consumed  in  starts  and  stops. 

(9200  -  2800)  -r-  (15  -  5)  =  640  ft.  pr  min. 

Using  the  foregoing  as  a  basis,  the  data  on  the  proposed  dump 
may  be  estimated. 

Pit  Haulage  on  Mesabi  and  Elsewhere. — Some  examples  of 
pit  haulage  on  the  Mesabi  are  noted  in  the  following.  The 
Shenango  iron  mine  has  an  average  waste  haul  of  2J^  mi.  The 
pit  is  150  ft.  deep  and  the  overburden  varies  from  50  to  80  ft. 
The  track  system  has  sharp  curves  and  the  grades  run  up  to  3 
per  cent.  Four  locomotives  are  used  in  the  pit,  and  in  addition 
to  the  regular  locomotives  for  handling  the  cars,  two  Lima  geared 
engines  are  used  as  boosters  on  each  ore  train,  Because  of  the 


DISPOSAL  OF  MATERIAL  171 

curves  and  grades,  one  50-ton  rod  engine  and  the  two  Limas 
can  handle  only  four  50-ton  cars  from  the  bottom  of  the  pit. 

On  a  contract  let  for  moving  some  eight  million  cubic  of  over- 
burden from  the  Buffalo  &  Susquehanna  iron  mine,  the  dump 
distances  varied  from  2J^  to  3J^  mi.  To  keep  four  shovels  busy, 
ten  55-ton  locomotives  operated  ten  trains,  each  made  up  of 
ten  12-cu.  yd.  air  dump  cars. 

At  the  Agnew  iron  mine,  both  mining  and  waste  dumping  are 
confined  to  40  acres.  The  overburden  is  50  to  60  ft.  thick,  and 
the  pit  is  135  ft.  deep,  and  covers  about  15  acres.  The  waste 
dump  is  150  ft.  high  and  covers  about  25  acres.  Here  a  50-ton 
rod  engine  can  handle  only  five  7-cu.  yd.  cars,  and  to  reach  the 
top  of  the  dump  four  switchbacks  are  used.  The  remainder 
of  the  ore  at  this  mine  will  have  to  be  won  by  other  methods. 

At  one  of  the  Swedish  magnetite  mines,  the  shovels  load  ore 
into  12-ton  side  dump  cars  which  are  hauled  to  the  scales  and 
breaker  in  five-car  trains  by  12-ton  switching  locomotives.  This 
is  unusually  light  equipment  for  such  service,  but  the  haul  is 
very  short. 

The  Utah  Copper  Co.  at  one  time  used  small  narrow  gauge 
dump  cars  on  the  upper  benches.  These  were  loaded  with  ore 
and  hauled  to  chutes  where  the  ore  was  dumped  down  to  a  lower 
level  and  reloaded  by  shovels  into  standard  cars.  The  steep 
hillside  made  it  difficult  at  first  to  run  standard  gauge  equipment 
to  the  highest  benches,  but  permitted  the  chute  arrangement. 

Where  pits  are  served  by  inclined  planes  the  transportation 
problem  is  entirety  different;  it  becomes  one  of  hoisting,  and  as 
such  may  be  considered  common  to  any  system  of  mining.  It 
may  be  mentioned  in  passing,  that  a  .continuous  traveling  chain 
or  cable  haulage  system  has  been  used  in  Europe  and  South 
Africa  for  gathering  small  cars  over  large  areas.  In  the  brown- 
coal  pits  in  Germany,1  small  cars  are  loaded  at  a  number  of  points 
and  are  moved  to  a  common  dumping  point.  The  cars  are  hand 
trammed  from  drifts  and  crosscuts  over  relatively  short  lengths 
of  track,  which  may  converge  at  a  common  point  or  which  may 
be  parallel  and  terminate  in  a  common  track  transverse  to  the 
drifts.  A  double  track  equipped  with  chain  haulage  (Kettenbau) 
serves  the  secondary  tracks  or  the  common  point.  The  chain, 
consisting  of  4  in.  links,  is  motor  driven  by  a  sprocket-wheel  and 
gears  at  the  end  of  the  run.  A  plate,  with  a  V  slot,  projects  up- 

1  YOUNG,  J.  G. :  Former  reference. 


172  STEAM  SHOVEL  MINING 

ward  from  the  end  of  each  car  and  engages  with  the  links  of  the 
chain.  The  chain  is  supported  by  the  cars,  spaced  at  20  to  40  ft. 
intervals,  but  it  is  carried  around  corners  on  guide  sheaves.  At 
all  turns  the  track  is  so  graded,  that  the  cars  gain  speed  on  the 
chain  and  disengage  themselves,  the  chain  here  .being  elevated 
to  permit  this.  They  then  run  by  gravity  around  the  turn  and 
are  again  picked  up  by  the  sag  of  the  chain  to  be  hauled  along  the 
next  tangent.  One  or  more  runs  may  be  necessary  in  a  given 
pit.  Loads  are  taken  out  on  one  track  and  empties  returned 
on  another.  The  incline  giving  access  to  the  pit  is  also  served 
by  a  chain.  The  system  is  almost  automatic,  delivering  the 
loads  to  the  tipple  and  returning  the  empties  with  .but  little 
manual  assistance  except  at  the  points  where  the  cars  are  attached 
and  removed. 

DUMPS 

The  disposal  of  overburden  removed  from  orebodies  often  pre- 
sents one  of  the  most  difficult  problems  in  open  pit  work.  It 
must  be  transported  as  cheaply  as  possible,  and  dumped  on 
areas  proven  to  have  no  underlying  open-cast  deposits,  and  where 
it  will  not  have  to  be  rehandled.  Available  dump  arenas  are  often 
restricted  due  to  topography,  local  ordinances,  rights  of  way  or 
ownership  by  others.  Sometimes  provision  must  be  made  for 
the  segregation  of  certain  material  for  probable  future  treatment. 
These  factors  require  that  dumps  be  built  in  various  ways.  It  is 
advisable  to  secure  if  possible,  all  probable  dump  area  require- 
ments well  in  advance  of  operatons.  * 

On  the  Mesabi1  dumps  are  classified  according  to  their  posi- 
tion, the  manner  in  which  they  are  started  and  the  trackage 
arrangements  and  operation.  There  are  side  hill  or  escarpment 
dumps,  trestle  dumps,  slush  dumps,  muskeg  or  lake  dumps 
and  caved  ground  dumps. 

Hillside  and  Escarpment  Dumps. — A  hillside  or  escarpment 
often  makes  an  excellent  starting  place,  as  the  track  may  be 
laid  on  the  contour  or  edge  and  dumping  started.  The  track  is 
then  thrown  horizontally  outward  on  the  dumped  material  and 
the  dump  height  is  rapidly  built  up.N  The  Ontario  Hydro-Electric 
Power  Commission  started  a  dump  from  the  edge  of  a  river 
escarpment  averaging  65  ft.  high.  The  two  mile  track  from  the 
canal  to  the  dump  was  laid  on  a  1  per  cent,  up  grade,  permitting 

1  Davenport,  L.  D.,  previous  reference. 


DISPOSAL  OF  MATERIAL  173 

a  50-ton  electric  locomotive  to  haul  ten  20-cu.  yd.  cars.  Cheap 
dumping  was  thus  easily  and  quickly  acquired.  The  Nevada 
Consolidated  and  Utah  Copper  Companies  have  utilized  side 
hill  dumps  to  good  advantage. 

Mesabi  Dumps. — The  details  of  dumping  operations  on  the 
Mesabi  vary  with  each  stripping  job  and  depend  on  the  equip- 
ment used,  size  of  job,  type  of  dump  and  other  conditions. 

If  possible,  a  dump  is  selected  on  a  low  piece  of  ground  sloping 
away  from  the  initial  dumping  point,  and  at  a  good  elevation  to 
take  care  of  the  proposed  over-burden.  The  dump  is  started 
by  backing  the  trains  out  on  the  dump  track  and  dumping  the 
cars  alternately  on  both  sides  of  the  track.  Next  the  track 
is  jacked-up  and  the  operation  repeated  until  the  desired  dump 
height  is  attained.  Fanning-out  is  then  started  by  throwing  the 
track  sideways  4  ft.  at  a  time  and  tbus  widening  the  dump. 
The  best  length  of  this  type  of  dump  seems  to  be  from  1200  to 
1500  ft.  The  outer  rail  of  the  track  is  elevated  a  little  to  prevent 
cars  going  over  in  dumping.  If  the  cars  are  hand-dumped  the 
rail  elevation  must  not  be  so  much  as  to  make  them  difficult  to 
dump,  but  if  the  cars  are  loaded  slightly  heavy  on  the  dumping 
side,  tr^is  will  be  counter-balanced.  Straight  dumps  are  some- 
times preferred  to  curved  ones  if  sufficient  length  can  so  be 
maintained.  The  reason  for  this  is  that  the  track  is  easier  to 
throw  and  does  not  bind,  but  the  interpolation  of  switchpoint 
rails  at,  say  75  ft.  intervals,  gives  sufficient  flexibility  to  the  track, 
so  that  little  difficulty  is  really  experienced. 

The  three  methods  in  common  use  on  the  Mesabi  are  described 
as  follows: 

First  method:  A  side  plow  or  "  dozer"  is  used  to  level  off  the 
dump  to  the  height  of  the  track  for  a  width  of  about  5  feet.  The 
track  is  then  jacked  up,  lined  over  3  or  4  ft.  and  blocked  up  so 
that  it  will  carry  the  cars  but  not  the  locomotive.  Dumping 
is  then  started  at  the  end  nearest  the  pit,  and  a  shoulder  is  carried 
toward  the  further  end  of  the  dump  so  that  the  track  has  ballast 
and  can  support  the  locomotive  as  the  shoulder  is  advanced. 
When  the  limit  of  the  dump  is' reached,  all  the  material  that  can 
be  dumped  is  placed  on  the  end  length  and  the  remaining  track 
is  filled  to  the  limit,  working  back  to  the  beginning  of  the  dump. 
The  dozer  is  then  used  again  and  the  operations  are  repeated. 

Second  method. — A  plow  having  a  spread  as  wide  as  30  ft.  is 
used  to  level  off  the  dump  18  in.  below  the  track.  The  dump  is 


174  STEAM  SHOVEL  MINING 

then  refilled  and  the  spreader  used  until  the  limit  of  spread  has 
been  reached.  The  last  plowing  is  made  level  with  the  track, 
which  is  then  lined  over  12  to  15  ft.,  and  the  operations  can  then 
be  repeated.  This  method  is  used  with  20-cu.  yd.  cars,  heavy 
equipment  and  a  track  shifter. 

Third  method. — The  track  is  made  safe  for  both  cars  and  loco- 
motive, and  the  first  train  out  is  dumped.  The  dump  crew  then 
levels  off  the  dirt,  and  lines  the  track  over  a  foot  or  more  if  pos- 
sible, along  that  part  of  the  dump  just  filled.  After  the  track  is 
ballasted,  the  next  train  is  dumped  further  along  and  the  next 
section  of  track  lined  over  as  before,  working  toward  the  end  of 
the  dump.  With  a  high  dump,  several  trains  may  be  emptied 
before  a  sufficient  shoulder  is  formed  to  allow  the  track  to  be 
lined  over.  The  crew  levels  the  dirt  and  throws  the  track  over 
between  trains.  With  this  method  there  is  always  room  to 
dump  a  train. 

With  the  first  and  second  methods,  a  dump  crew,  consisting 
of  a  foreman  and  one  or  two  men,  is  required  on  each  dump  both 
shifts.  A  track  crew  is  also  required,  consisting  of  a  foreman  and 
fourteen  or  more  men,  working  day  shift  only.  Under  ordinary 
conditions  a  crew  of  this  size  can  handle  the  track  work  on  four 
dumps.  With  the  third  method  a  foreman  and  six  men  on  each 
shift  can  handle  all  the  work  required  for  one  dump.  Each 
dump  is  provided  with  a  shanty  6  ft.  X  8  ft.  for  sheltering  the 
dump  crews.  There  is  also  a  16  ft.  X  16  ft.  shelter-house  cen- 
trally placed  within  easy  reach  of  all  the  dumps,  where  the  track 
crews  can  eat  and  spend  their  lunch  hour.  At  night  stripping 
dumps  are  lighted  by  kerosene  or  gasoline  torches,  powerful 
acetylene  lamps  of  the  portable  type  or  electric  lights  when 
practicable. 

Trestle  Dumps. — Trestle  dumps  are  used  in  many  cases  on  the 
Mesabi,  where  the  topography  is  flat.  They  are  somewhat  ex- 
pensive to  start  and  may  be  troublesome.  These  may  be  con- 
structed so  that  the  unfilled  trestle  work  carries  only  the  empty 
cars,  or  the  entire  train.  The  former  are  more  usual,  and  the 
Mesabi  practice  is  to  build  these  trestles  of  round  timber  with 
3  or  4  post  bents,  spaced  on  16  ft.  centres,  and  from  16  to  25  ft. 
high.>  The  trestle  legs  are  legs  from  8  to  12  in.  in  diameter, 
stringers  10  to  14  in.,  braces  3  to  5  in.,  and  8  ft.  railroad  ties  are 
used  for  caps.  The  legs  are  set  on  cross-sills,  are  given  a  batter 
of  2%  in.  per  ft.,  and  are  cross-braced  and  longitudinally  braced. 


DISPOSAL  OF  MATERIAL  175 

The  stringers  are  placed  above  the  caps  and  are  spiked  with 
drift  bolts.  Bents  less  than  4  ft.  high  are  not  built,  blocking  or 
cribs  of  old  ties  being  used  for  the  transition  from  earth  to  trestle. 
Filling  is  started  by  pushing  cars  out  on  the  trestle  ahead  of  the 
locomotive  and  dumping  several  on  one  side  one  at  a  time.  As 
they  are  dumped  the  empties  are  pushed  out  on  the  trestle  and 
others  are  dumped  on  the  opposite  side.  Heavy  dumping  on  one 
side  will  cause  undue  strain  on  the  legs.  As  soon  as  the  trestle 
has  been  filled  for  its  entire  length,  the  track  is  shifted  to  one 
side  and  dumping  continued  so  that  the  dump  is  widened.  The 
trestle  is  usually  so  located  that  the  dump  can  be  fanned  out 
from  both  sides.  If  sufficient  room  is  available,  the  trestle  is 
continued  far  enough  to  start  several  dumps  at  intervals  along 
its  length.  It  is  considered  good  practice  to  keep  the  edge  of  the 
dump  straight,  as  this  facilitates  the  throwing  of  the  track. 
When  the  limiting  horizontal  distance  has  been  reached,  it  is 
common  practice  to  throw  the  track  back,  raise  it  up  and  make 
a  new  level  by  working  back  over  the  area  already  filled.  An- 
other method  is  to  build  a  second  trestle  on  the  first  dump  and 
then  to  start  a  second  deck  in  the  same  manner  as  the  first.  The 
cost  of  such  dumps  has  been  given  at  from  $2.50  to  $5.00  per 
linear  foot.  . 

x  Slush  Dumps. — A  slush  dump  may  be  made  by  the  use  of  a 
trestle,  strong  enough  to  carry  the  loaded  train,  and  fitted  with 
an  apron  6  to  8  ft.  wide  on  the  dump  side.  The  material  is 
dumped  from  the  cars  onto  the  apron,  and  from  here  it  is  washed 
down  the  bank  by  water.  <  To  do  this  a  3  or  4  in.  pipe  line,  per- 
forated with  J^  in.  to  ^  in.  holes  at  short  intervals,  is  laid  along 
the  upper  edge  of  the  apron  against  the  ends  of  the  ties.  In 
some  cases  2  in.  hoses  have  been  used  for  sluicing.  At  one 
property,  on  the  shore  of  a  lake,  a  permanent  trestle  was  built  at 
an  elevation  of  about  100  ft.  above  the  lake  and  capacity  for 
150,000  to  200,000  cu.  yds.  was  provided  without  shifting  tracks. 

The  advantages  of  the  method  is  that  considerable  material 
can  be  moved  without  shifting  track,  and  hence  no  track  crew  is 
required,  and  the  dumping  space  is  always  ready  to  receive  the 
cars.  Although  the  pipe  may  be  laid  in  sections  so  that  water 
will  not  be  wasted,  considerable  is  required.  During  freezing 
weather  other  dumping  locations  must  be  used. 

Swamp  and  Lake  Dumps. — Muskeg  swamps  are  to  be  avoided 
as  dump  sites.  The  dumps  often  slide  or  settle  suddenly  in  spots 


176  STEAM  SHOVEL  MINING 

leaving  the  track  hanging  or  taking  the  track  and  train  over 
the  edge.  'In  attempting  to  fill  a  dump  trestle  across  a  muskeg 
swamp,  the  surface  of  the  swamp  is  often  bulged  up  as  high  as 
the  settled  dump,  making  dumping  impossible,  but  by  building 
the  trestle  along  the  edge  of  the  swamp,  the  muskeg  can  some- 
times be  forced  ahead  of  the  dump.  When  used  intermittently 
they  are  considered  less  dangerous. 

With  dumps  that  are  fanned  out  in  ponds  or  lakes  there  is 
considerable  danger  of  sudden  settling  along  the  edge.  The 
action  of  the  water,  agitated  by  the  material  being  dumped,  so 
undercuts  the  face  of  the  dump  that  it  suddenly  sloughs  off. 
Water  as  shallow  as  5  ft.  has  been  known  to  cause  this  trouble 
which  may  be  aggravated  by  the  sliding  or  settling  of  ooze  and 
mud. 

Dumps  on  Caved  Ground. — On  the  Mesabi,  caved  ground, 
above  underground  workings,  is  sometimes  used  for  dumps.  It 
is  decribed  as  follows:  The  additional  weight  of  the  dump  does 
not  greatly  affect  the  weight  on  the  underground  timber,  and 
filling  the  caves  prevents  surface  water  from  collecting  and  break- 
ing through  into  the  lower  workings.  The  expense  of  pumping 
water  from  the  caves,  frequently  necessary  in  older  underground 
mines,  is  eliminated  by  this  method  of  filling  the  sunken  areas. 
Blasting  underground  rooms  causes  the  dump  to  settle,  but  ad- 
vance information  to  the  dump  foreman  on  this  permits  him  to 
plan  his  work  accordingly.  Dumps  of  this  kind  are  usually 
started  from  a  trestle. 

Copper  Mine  Dumps. — At  the  great  western  porphyry  copper 
mines,  the  building  of  dumps  is  largely  governed  by  the  terrain. 
The  country  is  hilly  or  mountainous  for  the  most  part,  and  advan- 
tage is  taken  of  slopes,  gulches  and  side  hills.  Overburden  is 
taken  from  a  much  greater  range  of  altitude  than  on  the  Mesabi, 
and  this  requires  that  dumps  be  located  at  different  elevations, 
otherwise  grades  would  be  excessive  for  reasonable  distances. 
Overburden  from  the  different  benches  is  consigned  to  the  dump 
sites  best  suited  to  give  low  costs.  Such  ground  is  often  limited 
and  consequently  the  areas  and  heights  and  trackage  arrange- 
ment of  the  dumps  vary  widely.  Very  little  trestle  work  is  used 
in  starting  these.  In  some  cases  the  same  dump  sites  have  been 
used  to  take  care  of  overburden  from  different  bench  levels  by 
carrying  them  in  two  or  more  decks;  material  from  the  lower 
benches  being  used  for  the  lower  deck  and  that  from  upper 


DISPOSAL  OF  MATERIAL  177 

benches  for  the  upper  deck.  The  tracks  on  the  dumps  are  usu- 
ally on  an  ascending  grade  of  at  least  1  per  cent,  but  may  be 
higher.  When  the  position  and  area  is  suitable  the  track  may 
form  a  horse  shoe  so  that  the  loaded  trains  come  in,  dump  and 
continue  on  around  to  the  return  track.  This,  of  course,  turns 
the  train  around,  so  that  if  the  relative  position  of  cars  and  loco- 
motive is  to  be  kept  the  same  at  the  shovel,  the  train  must 
run  in  on  a  wye  spur  elsewhere  before  returning  to  the  shovel.  If 
the  dump  track  is  dead  ended,  as  is  usual,  the  end  rails  are  ele- 
vated and  supported  on  a  cribbing  of  railroad  ties.  Several  ties 
are  lashed  over  the  end  rails  to  act  as  a  wheel  stop  in  case  a  car 
should  be  backed  in  too  far.  This  end  cribbing  is  moved  out  as 
the  dump  is  fanned  out  and  in  so  doing  the  length  of  the  track  is 
slightly  shortened  at  each  move  on  account  of  the  dump  slope. 
The  use  of  switch  point  rails  at  frequent  intervals  permits  the 
track  to  be  flexed  out  over  a  long  arc  so  that  the  end  cribbing 
need  not  be  moved  too  frequently.  Every  effort  should  be 
made  to  avoid  train  congestion  or  delays  on  the  dumps,  and  for 
this  reason  it  is  often  economical  to  double-track  the  lines  to  a 
big  dump  as  well  as  have  several  separate  independent  dumping 
points. 

^  Height  of  Dumps. — The  question  as  to  what  is  the  best  height 
to  carry  dumps  depends  on  such  things  as  the  character  of  the 
material,  the  weather  conditions,  the  weight  of  equipment  and 
the  type  of  dump. 

The  Mesabi  waste  dumps,  often  covering  from  80  to  200 
acres  or  more,  range  from  25  to  60  ft.  high.  <\  At  Hibbing  the 
surrounding  country  is  quite  flat  and  the  waste  dumps  are  of 
more  or  less  uniform  depth.  Here  it  is  considered  that  the  most 
economical  height  is  not  exceeding  50  feet,  because  when  they 
exceed  this,  the  dirt  has  a  tendency  to  collect  on  the  slopes  and 
form  shoulders.  In  time  these  become  quite  heavy,  break  loose 
and  slide  to  the  bottom,  and  in  doing  so,  it  not  infrequently 
happens,  that  the  dump  breaks  back  of  the  edge  20  to  30  ft. 
and  takes  the  track  out  with  it.  It  is  also  found  that  high  dumps 
settle  much  more  than  lower  ones,  and  it  requires  a  larger  amount 
of  work  to  keep  up  the  track.  When  it  is  necessary  to  build 
higher  than  40  or  50  ft.,  a  second  30  or  40  ft.  dump  is  put  on 
top  of  the  first  after  it  has  thoroughly  settled.  Higher  dumps 
in  level  country  may  also  require  heavier  adverse  grades  and 
increase  the  transportation  cost.  Under  average  conditions, 

12 


178  STEAM  SHOVEL  MINING 

dumps  of  this  material  from  25  to  40  ft.  high  seem  to  give  the 
best  results,  but  from  necessity  some  have  been  carried  in  part 
up  to  87  ft. 

The  dumps  at  the  porphyry  copper  mines  are  extremely  vari- 
able in  height  because  the  terrain  is  very  steep  and  irregular 
and  because  of  the  necessity  of  utilizing  to  the  fullest  extent 
all  suitable  ground.  In  Nevada  the  dumps  range  from  25  to 
150  ft.  high  and  give  little  trouble.  The  material  is  altered, 
decomposed  porphyry  and  does  not  have  as  much  tendency  to 
shelve  off  or  settle  as  the  Mesabi  overburden  of  glacial  drift  and 
gravel.  Also  the  dumps  are  not  subjected  to  heavy  rains. 
The  type  of  dump  cars  used  drops  the  material  from  a  greater 
elevation  so  that  it  is  more  firmly  packed.  However,  if  ideal 
conditions  could  be  chosen,  perhaps  these  dumps  would  be 
carried  about  75  ft.  high.  There  would  be  little  danger  of 
shelving  off  or  settling  with  this  height,  and  at  the  same  time 
the  amount  of  track  shifting  would  be  kept  fairly  low.  In 
Utah  the  material  is  somewhat  similar,  and  the  dumps  have 
been  formed  wherever  there  was  available  area.  Canons  and 
gulches  were  filled  up  without  regard  to  height  of  dump,  as  the 
all  important  thing  was  to  find  a  place  to  put  the  waste  in  this 
difficult  mountainous  location. 

In  the  anthracite  region  dumps  are  made  of  all  heights  and 
sizes,  though  there  is  said  to  be  less  maintenance  cost  with  heights 
of  about  25  ft.  Dumps  of  greater  height  settle  and  slip  easily, 
especially  in  wet  weather. 

Hard,  rocky  material  deposited  in  an  arid  climate  can  evidently 
be  carried  to  heights  of  100  feet  without  inconvenience,  and  will 
require  less  track  shifting;  while  soft  earthy  material,  or  sand, 
clay  and  gravel  deposited  in  a  wet  climate,  should  evidently 
be  kept  down  to  heights  of  25  to  40  ft.  because  the  saving  in 
track  shifting  in  using  greater  heights  will  be  more  than  offset 
by  settling  and  bank  troubles. 

Hydraulicking. — Hydraulicking  has  in  some  instances  been 
used  to  dispose  of  waste  material  and  to  build  dumps.  In 
one  of  the  smaller  brown-coal  pits  in  Germany,  the  upper  portion 
of  the  overburden,  consisting  of  sand  and  soil,  was  stripped  by 
hydraulicking  and  back-filled  into  the  lower  part  of  the  pit. 
Retaining  dams  were  put  in  on  the  toe  of  the  spoil  slopes,  and 
the  sluices  discharged  back  of  them.  The  remainder  of  the 
overburden,  however,  consisted  of  moderately  compact  shales 


DISPOSAL  OF  MATERIAL  179 

and  clays,  and  was  removed  in  two  benches  by  undercuttings, 
caving  and  shoveling  by  hand  into  cars. 

Hydraulicking  has  been  considered  as  a  possible  system  for 
stripping  in  the  anthracite  region,  but  scarcity  of  water  and  of 
areas  on  which  to  deposit  and  settle  the  refuse  render  the  method 
impractical  for  most  sections  of  the  country.  It  has  been  sug- 
gested, however,  that  where  the  refuse  could  be  flushed  into 
mine  openings  to  support  the  surface,  a  double  value  would  be 
obtained.  This  has  been  tried  with  fair  success. 

In  stripping  coal  in  the  Danville  district  of  Illinois  the  method 
has  been  successfully  used  and  given  low  costs.  Here  the  super- 
ficial glacial  deposit  is  hydraulicked  by  two  nozzles  1^  in.  and 
1J^  in.  in  diameter  connected  to  the  same  4  in.  main  delivery 
hose.  Each  nozzle  is  operated  by  one  man  and  delivers  about 
1000  gal.  per  min.  under  pressure  of  135  Ib.  per  sq.  in.  at  the 
pump.  The  water  supply  is  furnished  by  a  duplex  steam  pump, 
of  2000  gal.  capacity,  installed  at  a  nearby  river. 

The  spoil  is  washed  into  an  adjoining  valley  or  into  old  excava- 
tions. The  work  is  not  carried  on  in  freezing  weather,  but  suf- 
ficient stripping  is  accomplished  in  the  summer  to  permit  the 
mining  of  shale  for  brick  the  entire  year.  The  amount  of  soil 
moved  per  8-hr,  shift  by  this  method  is  said  to  vary  from  100 
cu.  yd.  in  tight  ground  to  2000  cu.  yd.  in  loose  ground. 

For  hydraulicking  to  be  successful  there  must  be  an  ample 
supply  of  water,  suitable  terrain  for  the  disposal  of  the  spoil 
and  reasonably  soft  or  loose  material  to  work.  The  operations 
are  confined  to  the  open  season.  Under  these  conditions  very 
low  costs  per  cu.  yd.  of  overburden  removed  can  be  attained. 


CHAPTER  VI 

THE  DETERMINATION  OF  A  POWER  SHOVEL  MINE 

p       PRELIMINARY  DATA  REQUIRED 

Maps  and  Sections. — It  will  be  assumed  that  an  orebody 
has  been  discovered  and  that  the  development  work  on  it  has 
progressed  far  enough  to  delineate  its  physical  characteristics. 
The  next  step  then  is  the  selection  of  that  method  of  mining, 
which,  applied  to  the  deposit,  will  result  in  yielding  the  highest 
economic  returns.  Such  a  selection  can  be  made  only  after 
careful  consideration  of  the  particular  conditions  surrounding 
the  problem  by  men  of  experienced  engineering  training,  sound 
business  judgment  and  an  honest  understanding  of  the  conserva- 
tion of  both  labor  and  natural  resources.  Given  an  orebody 
with  sufficient  development  work  to  show  its  probable  shape, 
size,  texture,  structure,  unit  value,  boundaries  and  relationship 
to  the  enclosing  formation,  the  solution  of  the  mining  problem 
may  then  be  undertaken. 

The  occurrence  and  character  of  the  deposit  may  be  such  that 
an  experienced  engineer  will  be*  readily  able  to  correctly  class 
it  as  a  deposit  requiring  extraction  by  some  underground 
method  or  extraction  by  open-pit  work.  On  the  other  hand  it 
may  be  of  such  a  nature  as  to  suggest  investigation  by  both 
methods,  and  it  is  such  a  problem  that  will  now  be  discussed. 

The  first  work  to  be  done  consists  in  the  preparation  of  accurate 
maps  and  sections  of  the  deposit.  These  will  be  based  on  under- 
ground workings,  drill  holes  and  the  general  geology  and  topog- 
raphy. The  maps  should  show  the  contours  of  the  surface  and 
of  the  top  and  bottom  of  the  orebody.  The  sections  (best  made 
on  cross-section  paper)  should  be  taken,  if  possible,  at  regular  in- 
tervals through  the  orebody — say  generally  not  closer  than  50 
ft.  nor  farther  apart  than  300  ft.,  with  100  ft.,  as  a  good  average. 
Two  sets  of  vertical  sections,  one  set  at  right  angles  to  the  other, 
are  desirable  and  may  best  be  taken  parallel  to  the  two  axes 
of  the  orebody.  These  sections  will  show  graphically  the  actual 
and  relative  thickness  of  both  ore  and  overburden,  and  may  also 

180 


A  POWER  SHOVEL  MINE 


181 


182 


STEAM  SHOVEL  MINING 


S002 


SOOI 


N001 


N002 


N00€ 


NOOfr 


NOOS 


NOOI 


NOOQ 


Nooe 


NOOOI 


NOOK 


N003I 


N00£l 


NOOH 


NOOSI 


A  POWER  SHOVEL  MINE 


183 


be  used  for  indicating  slope  lines  and  shovel  benches  and  banks 
of  a  preliminary  nature.  It  may  also  be  desirable  to  prepare 
sections  through  the  deposit  horizontally  at  definite  elevations 
on  which  will  be  shown  the  outline  of  the  ore  intercept.  These 
are  especially  useful  in  planning  definite  extraction  levels,  shovel 
benches  or  pit-bottom  elevations. 


2600E 


Let  us  illustrate  this  work  by  an  example  in  which  Fig.  38  is  a 
typical  topographic  map  of  the  surface  covering  the  orebody. 
On  it  will  be  found  surface  contours,  location  of  all  drill  holes, 
projection  of  any  important  underground  workings,  looationof 
cross-sections,  outline  of  the  developed  orebody,  possible  outline 


184 


STEAM  SHOVEL  MINING. 


of  shovel  pit  bottom  and  outline  of  shovel  pit  edge.  These  last 
two  outlines  would  in  practice  be  straightened  out  to  allow  for 
practical  pit  working  conditions.  This  map  also  shows  where 
the  orebody  would  probably  first  be  attacked  for  shovel  work 


because  the  overburden  is  here  thinnest  and  the  approach  is 
simplest. 

Fig.  39  is  a  typical  vertical  section,  taken  at  A- A'  on  Fig.  38, 
of  the  orebody  and  shows  the  surface,  the  drill  holes  and  under- 
ground workings,  the  boundaries  of  the  determined  orebody  and 
the  proposed^average  pit  slope  lines. 


A  POWER  SHOVEL  MINE 


185 


Fig.  40  is  a  map  showing  the  contour  of  the  bottom  of  the  ore- 
body,  and  is  useful  for  either  pit  or  underground  work.  Con- 
tours of  the  top  of  the  orebody  (Fig.  [41) may  by  tracings  be 
superimposed  to  advantage. 


M 


To  further  illustrate  the  use  of  such  maps,  Figs.  42,  43  and  44 
are  here  given  showing  some  actual  well  known  pit  operations. 

Fig.  421  is  a  plan  of  the  pits  of  the  Nevada  Consolidated  Cop- 
per Company,  of  Ely,  Nevada. 

1  Eighth  Animal  Report,  Nevada  Consolidated  Copper  Company. 


186 


STEAM  SHOVEL  MINING 


POWER  SHOVEL  MINE 


Fig.  43  is  a  series  of  vertical  sections 
taken  through  the  pit  workings  and  ore- 
body.  These  show  clearly  the  advanced 
state  of  the  work  as  it  appeared  on 
January  1,  1915,  some  seven  years  after 
the  beginning  of  operations. 

Fig.  44  is  a  plan  of  the  pit,  dumps  and 
general  surface  plant  of  the  Commodore 
mine  of  Virginia,  Minnesota.1  The  opera- 
tions here  were  made  unusually  severe  on 
account  of  the  limited  area  (40  acres), 
depth  and  shape  of  the  orebody,  and  yard 
facilities.  Seven  hundred  thousand  tons 
of  ore  had  been  mined  through  under- 
ground operations  when  it  was  decided  to 
change  to  open  pit  mining.  To  complete 
the  stripping  it  was  necessary  to  dump 
800,000  cu.  yd.  on  the  Commodore  40 
acres,  over  20  acres  of  which  composed 
the  stripping  area  of  the  open  pit.  The 
waste  dump  finally  reached  a  height  of  87 
ft.  and,  as  the  top  of  the  deepest  ore 
stripped  was  114  ft.  below  the  dump 
bottom,  some  of  the  overburden  was  ele- 
vated 201  ft.  with  the  trackage  shown. 
From  shovel  to  dump  there  were  four 
switch-backs  on  a  5  per  cent,  grade. 

With  the  aid  of  such  plans  and  sections 
as  illustrated  by  Figs.  38,  39  and  40,  com- 
putations may  be  made  which  will  show 
the  ratio  of  overburden  necessary  to  mine 
the  ore.  A  convenient  form  of  keeping 
the  calculations  made  up  from  these  cross- 
sections  is  given  on  page  190. 

Such  maps  arc  also  used  to  show  the  work 
necessary  for  proper  approaches  and  yards, 
the  capacities  of  possible  dump  areas  and 

1  Bayliss,  M'Neil  &  Lutes — Mining  Methods 
on  the  Messabi  Range.  T.  L.  S.  M.  I.  18th  An- 
nual Meeting. 


187 


1 

613. 

Tons 
remaining 

Tons 
profitable 

| 

IN 

«l 

a 

Q 

O 

1      "S 

O         30; 

g 

o          a3 
EH           P. 

-M 

fa 
0 

O 
CQ 

L  ATI  ON 

11  = 
11° 

d 

p 

r  f"{ 

9 

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g 

B 

a 

o 

Mfi 

li° 

! 

III 

.1 
i 

Distance 
between 
sections 
feet 

'a 

0 

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188 


STEAM  SHOVEL  MINING 


A  POWER  SHOVEL  MINE 


189 


190 


STEAM  SHOVEL  MINING 


TABULATION  OF  OVERBURDEN 


Sec.  no. 

Distance 
between 
sections 
feet 

Total 
sq.  ft. 
waste 

Cubic 
feet 
waste 

Cubic 
yards 
waste 

Ratio  waste 
cu.  yd.  to 
1  ton  ore 

Remarks 

1  N.S. 

(Comp 

lete  se 

ries  of 

sectio 

ns,  say,  Nor 

th  and  South) 

Totals 

E 

(Comp 

lete  se 

ries  of 

sectio 

ns  at  right 

angles  to  the  extreme 

easter 

n  N-S 

sectio 

n) 

Totals 

'W 

(compl 

ete  se 

ries  of 

sectio 

ns  at  right 

angles  to  the   extreme 

weste 

rn  N- 

S  secti 

on) 

Totals 

Total 

Ends 

Corners 

NE 

(four, 

three- 

quarte 

r  secti 

ons  of  trunc 

ated    cones    not  taken 

SE 

care  of 

by  th 

e    abo 

ve  sec 

tions)     . 

.    NW 

sw 

•    Total 

Corners 

Grand 

Totals 

such  other  data  as  may  be  required  in  case  open-pit  work  is  to 
be  considered  in  detail.  They  will  be  used  to  estimate  the  a- 
mount  of  development  work  required  in  order  to  extract  a  giyen 
thickness  and  area  of  the  deposit  and  to  indicate  where  this  work 
should  be  done,  the  surface  area  likely  to  be  affected  by  caving- 
mining  operations  and  such  other  data  as  may  be  required  in 
case  underground  methods  are  to  be  considered  in  detail.  In 
either  class  of  mining,  they  are  indispensable  to  accurate  work. 
Local  Costs  and  Conditions.— The  next  study  is  that  of  the 
probable  operating  cost  to  be  obtained,  employing  such  methods 
of  mining  as,  under  the  local  conditions,  suggest  themselves  as 
adaptable.  The  computing  of  results  which  may  later  be  ful- 
filled in  practice,  is  largely  based  on  past  performance,  experience, 
and  proper  allowance  for  the  effect  that  such  local  conditions  as 
climate,  topography,  abundance  and  efficiency  of  labor,  cost  of 


A  POWER  SHOVEL  MINE  191 

supplies,  nearness  to  market,  transportation  facilities,  adjoining 
holdings  and  any  other  local  factors  that  may  have  a  bearing  on 
the  results. 

>  Initial  Time  and  Capital  Required. — Often  the  initial  period 
of  time,  and  'very  generally  the  initial  capital,  required  to  bring 
a  mine  to  a  state  of  self-support,  are  factors  of  great  weight  in 
determining  'the  method  of  attack.  > 

y  Other  General  Considerations. — In  case  the  product  is  sub- 
ject to  wide  fluctuations  in  selling  price,  then  flexibility  of  out- 
put without  sacrifice  of  efficiency  is  a  very  desirable  feature,  and 
should  be  given  weight  in  the  decision.  Again,  it  may  be  that 
one  method  of  mining  will,  with  little  or  no  additional  expendi- 
ture, make  available  for  future  use  a  large  amount  of  contiguous 
material  of  low  present  value  but  possibly  great  future  value, 
which  may  be  rendered  probable  by  new  and  improved  methods 
of  treatment  or  other  factors  reasonable  to  expect.  As  an  ex- 
ample of  this,  mention  may  be  made  of  the  low-grade  oxidized 
overburden  and  ore  fringes  which  a^^ow  being  removed  from 
the  large  steam-shovel  deposits  of  copper  ore  of  this  country. 
Such  material  may  be  put  on  dumps  from  which  it  is  easily  and 
cheaply  available  for  future  improved  methods  of  treatment. 

Another  class  of  material  from  these  mines,  which  may  later 
be  treated  at  a  profit,  is  the  deeper  low-grade  primary  sulphides. 
This  may  at  first  be  classed  as  waste,  but  may  usually  be  left 
so  exposed  after  open  pit  mining  as  to  be  attacked  cheaply  after 
the  richer  material  has  been  removed;  whereas  underground  min- 
ing usually  leaves  it  more  difficult  and  often  impossible  to 
economically  reclaim. 

Where  two  methods  of  mining  a  deposit  are  open  for  adoption 
and  both  seemed  to  indicate  approximately  equal  profits,  that 
one  should  generally  be  adopted  which  would  yield  the  product 
of  greatest  gross  value.  In  other  words  it  would  be  conservation 
of  resources  without  unfair  sacrifice  of  net  returns. 

A  factor  of  great  importance  in  mining  many  deposits  is  the 
physical  character  of  the  ore.  In  the  case  of  lenses  of  massive 
sulphide  ores,  great  losses  have  been  incurred  in  the  past  because 
they  caught  fire  through  heat  generated  by  their  own  crushing. 
If  such  a  contingency  seems  at  all  probable,  it  is  evident  that 
many  of  the  factors  mentioned  may  be  of  much  less  importance 
than  the  elimination  of  the  fire  risk.  Again,  if  for  some  reason  it 
be  essential  to  preserve  the  ore  in  a  very  clean  state,  then  a 


192  STEAM  SHOVEL  MINING 

method  of  extraction  must  be  selected  which  will  insure  this,  even 
though  in  other  ways  it  be  less  desirable.  / 

Sound  Conclusion  on  Method  to  be  Recommended. — It  is 
apparent  that  no  fixed  rules  can  be  laid  down  for  the  selection 
of  a  mining  method.  This  must  be  made  only  after  careful 
consideration  of  all  of  the  individual  peculiarities  and  condi- 
tions of  each  deposit.  The  wonderfully  rapid,  cheap  and 
efficient  work  done  by  the  steam-shovel  in  recent  years  has 
rightly  attracted  much  enthusiastic  commendation  and  atten- 
tion. This  has  not  infrequently  led  to  the  expression  of  hasty 
opinion  that  properties,  which  should  really  be  worked  by  under- 
ground mining,  are  "  steam-shovel  propositions."  Upon  full 
and  careful  investigation,  the  classification  of  some  of  these 
problems  will  be  properly  changed  and  serious  initial  mistakes 
will  be  avoided. 

The  general  statement  may  be  made  that  power-shovel 
methods  are  rarely  justified  except  where  the  amount  of  excava- 
tion to  be  done  is  relatively  large.  An  approximate  idea  of  the 
amount  of  work  required  to  warrant  their  employment  may  be 
had  by  estimating  the  total  cost,  including  all  necessary  plant 
equipment,  of  removing  a  given  yardage  with  power-shovels 
(or  some  other  similar  means),  or  of  removing  a  much  smaller 
yardage  by  some  underground  method.  It  is  more  apparent 
each  year  that  machine-work  is  becoming  cheaper  than  hand- 
work whenever  the  amount  of  work  to  be  done  is  large  enough  to 
warrant  the  necessary  initial  capital  outlay. 

The  operating  cost  of  power-shovels  is  subject  to  considerable 
variation  dependent  on  local  conditions.  Operating  efficiency 
of  the  shovels  is  of  prime,  importance  and  depends  largely  on  a 
thorough  coordination  of  the  whole  working  scheme,  as  well  as 
upon  the  skill  and  cooperation  of  the  shovel-crews.  In  arriving 
at  an  estimate  of  the  unit  cost  of  excavating  in  a  new  problem, 
the  local  conditions  likely  to  affect  costs  will  be  studied.  In  case 
the  new  property  is  located  in  a  district  where  power-shovel 
mining  has  been  going  on  for  some  time,  the  engineer  will  have 
considerable  advantage  in  making  an  estimate.  He  will  as- 
certain what  costs  are  being  obtained  under  "  present  good 
practice,"  and  then,  making  allowance  for  structural  variations 
of  the  deposit,  grades,  dump-sites,  future  improvement  and 
other  such  conditions,  will  calculate  the  probable  cost  for  the 
deposit  under  consideration.  In  such  a  locality  it  will  usually 


A  POWER  SHOVEL  MINE  193 

be  easier  to  get  started  and  to  secure  efficient  crews.  On  the 
other  hand,  if  the  property  be  located  in  a  foreign  country  and 
far  from  any  work  of  this  class,  the  solution  of  the  cost  problem 
becomes  more  uncertain.  The  human  factor  in  the  complete 
organization  must  be  more  fully  considered  and  the  local  con- 
ditions will  all  have  to  be  worked  out.  Under  such  conditions 
a  larger  " factor  of  safety"  should  be  employed  in  estimating  the 
cost  in  order  to  cover  unforeseen  contingencies.  Cost  estimates 
seem  to  have  a  provoking  tendency  of  being  too  low,  rather  than 
too  high,  when  put  to  the  test. 

ILLUSTRATIVE  EXAMPLE  OF  THE  SOLUTION  OF  A  PROBLEM 

Hypothesis. — As  an  example  illustrating  the  solution  of  such 
a  problem,  let  us  assume  that  we  have  an  orebody,  such  as  shown 
by  Figs.  38,  39  and  40,  of  the  following  characteristics:  first,  it 
has  been  well  developed  by  churn-drill  holes  and  underground 
workings  and  has  been  carefully  mapped  and  sectioned;  second, 
this  work  shows  it  to  be  a  large  flat-lying  lenticular  deposit, 
covered  by  a  leached  overburden;  third,  the  ore  occurs  as  dis- 
seminated copper  and  iron  sulphides  in  a  partly  decomposed 
porphyry;  fourth,  it  is  of  low  grade  and,  in  order  to  show  a 
profit,  will  require  a  cheap  method  of  extraction;  fifth,  the  for- 
mation enclosing  the  orebody  is  of  similar  character  to  the  ore 
except  that  the  overburden  is  harder  and  more  silicious  while 
the  sides  and  bottom  are  less  decomposed  and  firmer;  sixth, 
the  few  underground  workings  show  that  they  require  close 
timbering  to  be  kept  open  for  any  length  of  time;  seventh,  the 
ground,  though  very  heavy  and  inclined  to  squeeze,  is  fairly  dry 
and  the  indications  are  that  the  ore  would  cave  readily  if  properly 
undercut. 

Engineering  Calculations. — Estimates  made  from  the  plans 
and  cross  sections  are  as  follows: 

Length  of  long  axis 1800  feet 

Length  of  short  axis 1100  feet 

Average  thickness  of  direct  overburden    245  feet 

Shallowest  thickness  of  direct  overburden ....  70  feet 

Greatest  thickness  of  direct  overburden 300  feet 

Average  thickness  of  main  orebody 96  feet 

Least  thickness  of  main  orebody 40  feet 

Greatest  thickness  of  main  orebody 115  feet 

Horizontal  area  of  main  orebody 30  acres 

13 


194  STEAM  SHOVEL  MINING 

Assuming  that  practically  all  of  the  valuable  metal  in  the  ore 
is  copper,  it  is  decided,  in  estimating  the  ore  tonnage,  to  draw  the 
line  between  ore  and  waste  at  assay  returns  carrying  less  than 
1.25  ;ilper  cent.  Cu.  However,  inasmuch  as  some  material 
carrying  less  than  1.25  per  cent.  Cu,  but  not  less  than  1  per  cent. 
Cu.,  would  have  to  be  removed  in  the  event  that  shovel  mining 
were  employed,  and  furthermore  as  such  a  method  would  leave 
exposed  an  additional  underlying  tonnage  of  material  which 
could  be  considered  as  ore  if  no  stripping  expense  were  charged 
against  it,  these  second  and  third  tonnages  are  also  computed. 
The  reason  for  drawing  the  line  between  ore  and  waste  at  assays 
under  1.25  per  cent.  Cu.  for  the  main  orebody,  and  at  assays 
under  1  per  cent.  Cu.  for  the  second  and  third  bodies  will  be 
explained  later. 

In  calculating  the  overburden  yardage,  the  first  thing  required 
is  the  preparation  of  a  preliminary  working  pit  layout.  Con- 
sidering all  development  work,  a  line  is  drawn  to  include  and 
circumscribe  the  orebody  it  is  proposed  to  mine  with  shovels. 
This  boundary  is  called  the  " crest  of  ore"  in  the  proposed  pit. 
A  second  line  is  drawn  say  about  20  ft.  outside  of  this,  and  called 
the  "toe  of  stripping."  Study  of  the  ground,  and  exposures  in 
some  railroad  cuts  in  similar  material,  indicate  that  slopes  at 
45°  should  stand  well  for  long  periods.  It  is  assumed  that  banks 
on  this  slope  could  be  worked  to  a  final  height  of  100  ft.,  provided 
that  between  such  banks,  berms  of  30  ft.  be  left  to  catch  any 
slides  or  loose  material  and  prevent  them  from  endangering 
the  workmen  and  equipment  working  lower  down  in  the  pit. 
It  will  be  assumed  that  in  the  earlier  stages  of  the  work  benches 
would  be  carried  only  50  ft.  in  height,  but  as  the  pit  limits  are 
gradually  reached,  two  50-ft.  banks  would  be  run  together  to 
form  one  100-ft.  bank.  In  this  way  steeper  average  slopes  from 
the  "toe  of  stripping"  to  the  "crest  of  stripping"  (viz.,  the 
final  pit  edge)  can  be  carried,  with  an  attendant  considerable 
reduction  in  overburden.  The  sections  thus  prepared  show  an 
average  slope  inclination  of  40°  to  the  horizontal,  and  are  taken 
the  same  for  both  ore  and  overburden. 

These  final  benches  are  drawn  on  the  ore-sections,  while  for 
the  ends,  sections  are  taken  at  right  angles  to  the  first  and  last 
of  the  ore-sections.  The  corners  between  the  two  sets  of  sections 
are  computed  as  being  %  sections  of  truncated  inverted  cones. 
From  the  completed  sections,  the  outline  of  the  edge  of  the 


A  POWER  SHOVEL  MINE  195 

final  pit  is  then  drawn  on  the  topographic  plan.  This  crest  of 
stripping  line  is  next  adjusted  to  give  a  practical  working  pit, 
allowing  for  practical  track-grades  and  curvature.  The  sections 
are  then  modified  to  conform  with  the  final  crest  of  stripping 
line.  A  study  of  the  sections  gives  a  good  idea  of  the  relative 
ratio  of  overburden  to  ore,  and  incidentally  indicates  where 
more  development  work  might  be  done  to  advantage.  In  this 
case  the  study  does  not  indicate  that  probable  tonnage  additions 
will  materially  alter  the  relationship  of  ore  to  overburden.  The 
area  of  the  final  pit-plan  is  found  to  cover  65  acres.  The  average 
thickness  of  overburden  over  this  area  is  200  ft. 

A  summary  of  the  tabulated  results  taken  from  the  sections 
is  as  follows:1 

(1)  Ore   assaying    1.25   per   cent. 

Cu.  or  better 12,000,000  tons;  Avge.  2.0  per  cent.  Cu. 

(2)  Ore  assaying  1.00  per  cent,  to 

1.25  per  cent.  Cu 600,000  tons;  Avge.  1.15  per  cent.  Cu. 

(3)  Ore  assaying  1.00  per  cent,  to 

1.25  per  cent.  Cu 2,000,000  tons;  Avge.  1.10  per  cent.  Cu. 

(4)  Overburden  required  to  be.  removed  to  mine  (1)  =  24,000,000  cu.  yd. 
Note:  (1)  is  concentrating  sulphide  ore  and  is  designated  as  the  main 

orebody. 

(2)  is  made  up  largely  of  material  carrying  copper  oxides  and  carbonates, 
and  overlies  (1).     It  is  not  considered  amenable  to  hydraulic  concentration, 
though  it  is  readily  leached. 

(3)  is  the  low-grade  sulphide  material  underlying  (1).     The  assays  show 
it  to  be  richer  than  (1)  in  iron  sulphides.     While  it  is  amenable  to  hydraulic 
concentration,  both  the  concentration  ratio  and  the  copper  content  of  the 
concentrates  are  low;  consequently  the  treatment  cost  per  pound  of  copper 
produced  from  such  material  would  be  somewhat  higher  than  for  the  main 
orebody. 

1  For  tonnage  estimates  of  this  character,  the  writer  prefers  accurate 
cross  section  methods  to  others.  They  are  graphic,  more  comprehensive, 
fit  in  well  with  the  actual  pit  plans,  leave  a  record  clearly  understood  and 
easily  added  to  as  desired,  and  are  of  great  aid  in  studying  the  trend,  form 
and  general  relationship  of  the  ore  deposit.  If  the  work  be  accurately  plot- 
ted and  if  the  volumes  be  calculated  on  the  theory  of  the  mean  proportional, 
or  by  the  prismoidal  formula,  the  results  will  be  quite  accurate.  As  a 
check  on  such  estimates,  the  triangular  prism  method  may  be  employed, 
and  will  be  found  quite  precise. 

Considerable  has  been  written  on  methods  and  general  principles  of 
estimating  the  tonnage  and  value  of  orebodies,  but  it  is  not  the  intention 
here  to  recapitulate  them.  It  is  assumed  that  the  reader  has  a  fair  knowl- 
edge of  such  special  work.  It  cannot  be  stated  too  emphatically  however 


196  STEAM  SHOVEL  MINING 

Because  of  the  character  of  the  material  classed  under  (2) 
and  (3)  its  extraction  would  not  be  profitable  by  underground 
mining.  In  the  event  of  mining  (1)  with  power-shovels  however 

(2)  would  have  to  be  mined  as  a  part  of  the  overburden,  while 

(3)  would  be  left  exposed  after  the  removal  of  (1).     In  this  event 
it  could  be  considered  that  neither  (2)  nor  (3)  be  required  to 
carry  any  stripping  expense,  all  of  this  having  fallen  on  (1). 
Furthermore  (2)  would  not  be  charged  with  any  mining  expense 
(except  for  a  possible  later  rehandling  charge  from   dumps) 
since  it  would  be  carried  as  overburden  removal  from  (1).     A 
mining  charge  would  have  to  be  made  against  (3)  however. 

Consideration  of  Shovel  Methods. — It  is  assumed,  after  a 
careful  study  of  the  cost  of  shovel  work  in  this  and  other  dis- 
tricts and  after  making  due  allowance  for  the  local  conditions, 
that  this  material  (ore  and  overburden)  can  be  excavated  for  an 
average  cost  of  32  cents  per  cu.  yd.  in  place. 

It  is  desired  to  bring  the  property  up  to  a  production  of  5,000 
tons  per  day  at  a  reasonably  early  date.  To  insure  a  steady 
output  of  this  amount  it  is  estimated  that  in  using  shovels,  ore 
must  be  exposed  for  a  length  of  about  1,000  ft.  and  for  a  width 
of  100  ft.  Study  of  the  plans  and  sections  indicates  that  this 
can  be  best  accomplished  by  beginning  to  strip  at  the  east  end 
where  the  overburden  is  shallowest.  The  required  exposure 
can  here  be  made  by  cutting  out  a  series  of  from  three  to  four 
benches  of  overburden  having  heights  of  50  ft.  and  leaving  30-f t. 
berms  between  them.  Five  million  cubic  yards  would  be 
removed  in  this  initial  work. 

The  actual  opening  up  of  a  shovel  mine  involves  other  civil 
and  mechanical  engineering  problems,  as  applied  to  each  indi- 
vidual case,  and  they  will  next  be  taken  up,  as  follows : 

1.  Proportion  of  overburden  to  ore,  taking  account  of  the 
depth  and  thickness  of  both,  and  the  vclume  of  overburden  in 
the  slopes  and  in  any  irregularities. 

2.  Location  of  the  most  desirable  approach,  or  approaches, 
considering  both  overburden  and  ore  removal,  and  the  volume 
of  material  to  be  removed  in  this  work. 

that  success  in  mining  open-pit  deposits  depends  on  a  thorough  examina- 
tion showing  conclusively  that  there  exists  a  sufficient  tonnage  of  ore  to 
warrant  the  project.  The  more  complete  and  precise  this  preliminary  in- 
formation is  the  more  correct  will  be  the  conclusions  and  the  better  will  be 
the  working-plans  evolved. 


A  POWER  SHOVEL  MINE  197 

3.  Location  and  cost  of  most  desirable  assembly  yard. 

4.  Location  and  layout  of  overburden  dumps,  giving  considera- 
tion to  length  of  haul,  grades,  capacity  and  differences  in  eleva- 
tion between  which  the  material  must  be  transported. 

5.  The  drainage  of  the  pit  and  ore,  if  important. 

6.  System  of  trackage  and  haulage  to  be  employed. 

7.  Selection  of  the  mechanical  equipment  to  be  employed. 
These  items  have  all  been  discussed  in  the  preceding  pages 

so  that  time  and  cost  studies  will  conclude  the  present  analysis. 

Three  means  of  approach  were  studied.  The  first  had  the 
disadvantage  of  long  heavy  grades;  the  second  was  unfavorable 
to  a  well  located  assembly  yard;  the  third  had  an  expensive 
200-ft.  cut  at  the  pit  entrance,  but  the  grades  were  easy,  and 
connections  to  the  proposed  assembly  yard  were  convenient. 
It  does  not  seem  likely  that  this  third  approach  would  have  to 
be  materially  altered  fer  late  operations,  as  the  bottom  of  the 
orebody  could  be  reached  by  means  of  spirals  or  switchbacks 
requiring  about  10,000  ft.  of  trackage  with  three  per  cent, 
adverse  grades.  This  approach  requires  the  removal  of 
1,000,000  cu.  yd.  Although  haulage  of  material  out  of  the 
pit  over  the  proposed  spiral  would  cost  considerable,  the 
topography  is  such  that  to  materially  lower  the  approach 
involves  the  removal  of  so  much  additional  yardage  that  the 
expense  would  not  be  justified  by  the  somewhat  lower  trans- 
portation costs,  and  furthermore,  initial  production  would  be 
considerably  delayed. 

Incidentally  an  approach  by  means  of  a  tunnel  was  considered 
but  this  was  found  to  be  much  more  costly  and  slower. 

The  third  approach  having  been  definitely  decided  on,  the 
assembly  yard  was  planned  at  its  lower  end  with  four  tracks,  each 
1,000  ft.  long  and  able  to  accommodate  a  full  train  of  22  standard 
50-ton  steel  cars. 

Study  of  the  topography  of  the  nearby  country  indicates  that 
preliminary  dumps,  sufficient  to  hold  six  million  cubic  place  yards 
of  the  initial  overburden  can  be  built  up  with  four  miles  of  track- 
age. These  track  positions  were  roughly  located. 

The  drainage  problem  is  often  quite  serious  when  working  pits 
in  wet  countries,  sometimes  requiring  a  pump  shaft  near  the  edge 
of  the  pit,  supplemented  by  a  system  of  drainage  drifts  beneath 
the  pit.  Fortunately  in  this  vicinity  the  climate  is  comparatively 


198 


STEAM  SHOVEL  MINING 


dry,  so  that  a  100-gal.  per  min.  pump,  placed  near  a  pit  sump, 
will  be  able  to  dewater  the  pit  of  all  catchment  waters. 

Next  a  time  study  was  made  to  see  about  how  long  it  would 
take  to  bring  the  mine  up  to  the  required  production.  Condi- 
tions are  such  that  it  is  believed  that  over  this  estimated  inter- 
val, an  average  of  four  100-ton  shovels  can  be  worked  two  shifts 
per  day  and  move  an  average  of  1,000  cubic  place  yards  per  shift. 
In  the  beginning  four  shovels  cannot  be  placed  to  advantage  but, 
as  the  work  advances,  this  number  can  be  used,  and  in  the  later 
stages  of  the  work  an  additional  one  or  two  shovels  can  be 
worked.  With  this,  and  the  auxiliary  equipment,  it  is  assumed 
that  two  million  cubic  yards  can  be  moved  per  year.  As  the 
initial  overburden  contains  five  million  cubic  yards,  and  the 
approach  contains  one  million  cubic  yards,  a  total  of  six  million 
cubic  yards  will  have  to  be  removed,  which  at  the  average  rate 
of  two  million  cubic  yards  per  year,  will  require  three  years  to 
accomplish. 

A  cost  study  of  the  task  is  estimated  as  follows: 


Approach: 

Earthwork,  1,000,000  cu.  yds.  @  5Q£ $500,000. 

Trackage,  3,500  ft.  @  $6,000/mile 4,000. 

Building  3  miles  of  R.  R.,  2  per  cent,  grade,  60,000. 

Assembly  yard: 

4  tracks— 4,000  ft 


5,000. 


$564,000. 


5,000. 


Preliminary  stripping: 

(To  expose  ore  1,000  ft.  X  100  ft.) 
Removing  5,000,000  cu.  yds.  @  35  ff 

Preliminary  dump  and  supply  trackage: 

(Allows  for  4  dumps  and  1  supply  track  and 
totals  19,000  ft.  of  trackage) 


1,750,000.       1,750,000. 


Excavating  60,000  cu.  yds. 
Track  and  construction . . 


40,000. 
20,000. 


Total 


Plant-buildings  and  equipment: 

(As  per  detailed  estimate  given  later) , 


Total  initial  expenditure . 
or  say  in  round  numbers 


60,000. 

$2,379,000. 


500,000. 

$2,879,000. 
$3,000,000. 


In  this  problem  it  will  be  assumed  for  simplicity  that  no  pur- 
chase price  is  placed  on  the  property,  that  no  indebtness  remains 
from  the  old  development  work,  and  that  ample  ground  for  dump- 


A  POWER  SHOVEL  MINE  199 

storage  has  been  acquired;  thus  there  will  be  built  up  a  suspense 
account  of  $3,000,000  before  the  property  is  brought  to  produc- 
tion. Of  this  amount  $1,750,000  is  for  initial  overburden  re- 
moval and  $1,250,000  is  for  building,  equipment,  and  general 
working  facilities.  By  some  method,  this  initial  capital  expendi- 
ture will  have  to  be  returned  as  the  ore  is  extracted.  If  evenly 
apportioned  over  the  12,000,000  tons  of  shovel  ore  developed,  the 
latter  amount  equals  without  interest  10.4  cents  per  ton.  Allow- 
ing three  years  for  the  preliminary  work  and  seven  years  for 
extracting  the  orebody,  the  life  of  the  operation  would  extend 
over  a  period  of  ten  years.  This  sum  of  $1,250,000  would  prob- 
ably be  spent  during  the  first  two  years  of  the  operations,  so  that 
interest  charges  must  be  calculated  for  a  period  of,  say,  nine 
years.  Interest  tables1  show,  that  the  amount  which  must  be 
set  aside  at  the  end  of  each  year  for  nine  years, — so  that  at  the 
date 'of  the  last  payment  this  sum  and  its  interest  (taken  at 
6  per  cent,  and  interest  being  compounded  annually  on  the  bal- 
ance) will  be  paid — will  be  $183,775.  The  total  sum  to  be  set 
aside  then  equals  $1,653,975,  or  at  the  rate  of  13.8  cents  per  ton 
of  ore  developed. 

It  will  further  be  assumed  that  an  average  sum  of  $1,250,000 
will  be  tied  up  in  a  deferred  stripping  suspense  account  over  a 
period  of  eight  years  of  the  operations.  This  is  due  to  the  neces- 
sity, during  the  earlier  years  of  the  work,  of  partly  stripping  a 
considerably  larger  area  than  that  actually  exposing  ore.  In 
other  words  to  expose  a  given  amount  of  ore  for  extraction  it  is 
not  only  necessary  to  completely  strip  such  ore  but  also  to  partly 
strip  a  large  amount  of  contiguous  territory  in  order  to  allow 
for  proper  working-slopes  and  benches.  In  the  later  years  of  the 
life  of  the  property  this  suspense  account  can  gradually  be  re- 
duced until  finally  absorbed.  In  the  meantime  some  provision 
should  be  made  for  the  interest  value  of  this  sum  in  suspense. 
Interest  tables2  show  that  at  the  end  of  eight  years,  $1,250,000  at 
6  per  cent. — interesting  being  compounded  annually — amounts 
to  $1,992.312.  As  a  proper  charge  per  ton  of  ore  extracted,  to 
carry  its  proportion  of  the  stripping  expensa,  has  been  deter- 
mined, the  $1,250,000  principal  will  automatically  be  absorbed 

1  ROBINSON,    J.  W. — Robinsonian    Building-Loan  Interest    Tables;  6th 
Edition,  Table  6. 

2  ROBINSON,    J.  W. — Robinsonian    Building-Loan  Interest    Tables;  6th 
Edition,  Table  1. 


200  STEAM  SHOVEL  MINING 

thereby,  but  the  interest  difference,  amounting  to  $742,312,  must 
be  charged  against  the  ore  tonnage.  This  amounts  to  6.2  cents 
per  ton  and,  when  added  to  the  initial  plant  equipment  and  general 
working  facilities  charge  of  13.8  cents  per  ton,  makes  a  total  of 
20  cents  per  ton,  of  which  about  9.6  cents  per  ton  is  required 
solely  to  cover  interest  on  the  principal. 

It  was  previously  estimated  that  to  strip  the  12,000,000  tons  of 
ore,  24,000,000  cu.  yds.  of  overburden  had  to  be  excavated,  or  an 
average  of  2  cu.  yds.  per  ton  of  ore;  also  that  the  average  cost  of 
excavating  this  material  (both  overburden  and  ore)  would  be 
32  cents  per  cu.  yd.  in  place.  The  estimated  complete  cost  per 
ton  of  mining  the  orebody  is  therefore  as  follows : 

Removing  2  cu.  yds.  of  overburden  @  32ff $0. 64 

Removing  %  cu.  yd.  of  ore  (equal  to  1  ton)  @  32 j£ 0. 16 

Initial  expenditure  and  interst  charge  redemption 0 . 20 

Total  cost $1 .00 

Consideration  of  Underground  Methods. — Of  the  many 
methods  of  underground  mining,  those  well  adaptable  to  a  soft 
low-grade  deposit  of  this  class  are  not  numerous.  The  fol- 
lowing ones  however  are  considered  worthy  of  study. 

Top-Slicing. — This  method,  as  employed  at  several  well 
operated  mines,  has  given  good  results.  When  carefully  worked 
it  gives  a  high  percentage  of  ore  recovery  because  the  general 
control  is  good,  and  shallow  portions  and  fingers  of  the  orebody 
can  be  closely  followed  out.  The  product  is  clean  and  the  method 
is  safe  for  the  miners.  It  has  the  disadvantages  however  of  a 
rather  high  cost  and  limited  flexibility  of  output.  Under  un- 
favorable conditions  the  cost  may  reach  $2.00  per  ton  while 
under  very  favorable  conditions  it  may  be  as  low  as  80  cents 
per  ton.  A  large  amount  of  timber  is  required,  both  for  support- 
ing the  openings  and  to  form  a  heavy  timber-mat  between  the 
ore  and  caved  overburden.  Ventilation  is  usually  difficult,  and 
this  results  in  heating,  which  lowers  the  efficiency  of  the  work- 
men. The  output  in  tons  per  man-shift  is  lower  than  with  some 
other  methods.  As  timber  and  labor  are  both  relatively  expen- 
sive at  this  property  it  is  estimated  top-slicing  would  cost  about 
$1.30  per  ton. 

Shrinkage-Slope  Methods. — These  methods  are  adaptable  to 
deposits  of  considerable  thickness,  horizontal  extent  and  regu- 
larity where  the  ground  is  self-supporting  enough  to  permit 


A  POWER  SHOVEL  MINE  201 

the  working  up  of  slopes  of  convenient  size  without  overhead 
support  or  protection,  and  where  it  is  believed  the  extraction 
drifts  (for  drawing  off  the  broken  ore  from  stopes  and  caving 
pillars)  may  be  kept  open  without  excessive  repair  costs.  Under 
these  conditions  the  method  is  safe,  the  cost  reasonably  low — 
say  from  70  cents  to  $1.00  per  ton, — a  high  percentage  of  fairly 
clean  ore  may  be  expected  and,  once  the  deposit  is  well  opened 
up,  the  operations  may  be  conducted  on  a  large  scale  with  con- 
siderable flexibility  of  output.  Much  preliminary  development 
work  is  required.  Care  must  be  used  in  carrying  up  the  shrink- 
age stopes  and  especially  in  seeing  that  the  pillars  cave  completely. 
The  ore  must  be  drawn  off  systematically  to  prevent  chimney- 
ing, otherwise  there  results  a  bad  mixing  of  waste  and  ore, 
lowering  the  grade  and  leaving  ore  unrecovered.  It  is  essential 
that  the  capping  follow  tha  ore  down  with  the  drawing,  as  other- 
wise large  unfilled  chambers  will  be  left  which  may  later  result 
in  dangerous  air-blasts  upon  the  sudden  collapse  of  large  areas 
of  capping.  The  method  is  not  adaptable  to  very  soft  or  run- 
ning ground,  or  to  deposits  of  great  irregularity  or  thinness. 
Considerable  capital  is  tied  up  in  broken  ore  in  the  stopes  before 
much  reserve  drawing  can  be  started.  This  may  add  as  much 
as  5  per  cent,  to  the  mining  cost  due  to  interest  charges.  Allow- 
ing for  these  factors,  the  deposit  under  consideration  would 
lend  itself  to  this  method,  provided  the  ground  proved  to  be 
sufficiently  self-supporting  to  permit  of  safe  stopes  and  reason- 
ably cheap  maintenance  of  the  extraction  drifts.  The  deposit 
is  however  very  soft  and  decomposed  and  contains  a  high  per- 
centage of  kaolin,  so  that  considerable  doubt  is  felt  about  this 
last  point. 

Block-Caving. — This  method  is  considered  because  it  is  known 
to  give  low  costs,  running  from  60  cents  to  90  cents  per  ton. 
When  applied  to  deposits  where  the  ore  is  of  good  grade  and  where 
the  fringe-rock  and  capping  are  poor  or  valueless,  there  is  serious 
objection  to  the  method  because  of  the  lack  of  control  over  the 
drawing  down  of  the  ore.  A  large  amount  of  waste  invariably 
gets  intimately  mixed  with  the  ore  and  this  either  seriously  lowers 
the  grade,  or  else  involves  heavy  loss  of  good  ore  which  has  be- 
come entrained  or  badly  diluted  with  waste.  Unless  sections 
of  the  orebody  can  be  drawn  fairly  evenly  these  losses  will  be  very 
serious.  Because  the  control  points  governing  the  draw  are 
usually  so  few  and  draw  each  from  a  number  of  divergent  feeder 


202  STEAM  SHOVEL  MINING 

points,  it  has  been  very  difficult  to  obtain  satisfactory  results. 
Consequently  it  cannot  be  recommended  for  the  orebody  under 
discussion. 

Branch-Raise  System. — This  system  has  been  successully 
employed  for  mining  several  of  the  low-grade  copper  deposits 
individually  very  dissimilar  as  to  their  shape,  dip,  structure  and 
ore  texture.  The  reported  costs  have  been  remarkably  low, 
ranging  say  from  35  cents  to  $1.00  per  ton  of  ore  delivered  to 
surface.  The  method  requires  considerable  initial  and  continu- 
ous development  work,  but  it  is  simple,  safe  and  flexible.  The 
control  gates  differ  from  those  used  in  block-caving  as  they  are 
here  placed  close  together  in  the  " finger  raises"  (10  to  12^£  ft. 
apart),  draw  only  from  one  feeder  point,  and  give  easy  access  for 
inspection  of  the  draw.  For  this  reason  even  drawing  may  be 
effected,  so  that  with  the  close  definite  control,  a  high  percentage 
of  tonnage  recovery,  without  a  serious  drop  in  grade,  may  be 
expected. 

Careful  consideration  of  these  various  methods  leads  to  the 
belief  that  the  branch-raise  system  will  be  the  best  underground 
method  to  consider  in  competition  with  the  open-pit  method. 

Detailed  estimates  indicate  that  an  average  mining  cost, 
including  current  development  work,  of  80  cents  per  ton  can 
be  attained  under  present  local  conditions. 

To  develop  and  equip  the  property  for  a  production  of  5,000 
tons  per  day  by  underground  mining,  it  is  estimated  will  require 
about  two  years.  This  will  cost: 

For  buildings  and  equipment $500,000. 

For  mine  development  work .  .  . $700,000. 

Total $1,200,000. 

Proportioned  over  the  tonnage  developed,  this  amounts  to 
10  cents  per  ton. 

After  the  property  has  been  brought  up  to  production,  viz., 
at  the  end  of  two  years,  the  current  cost  of  ore  extraction  will 
be  expected  to  carry  the  further  cost  of  development  work. 
To  avoid  wide  current  cost  fluctuations,  the  development  charges 
per  ton  will  be  based  on  the  estimated  average  cost  of  such  work 
over  the  life  of  the  mine,  although  this  figure  may  require  peri- 
odic adjustment.  It  will  be  assumed  then  that  this  initial  expen- 
diture of  $1,200,000  will  be  carried  in  suspense  over  eight  years 


A  POWER  SHOVEL  MINE  203 

(one  during  development  and  seven  during  extraction)  but  in 
gradually  decreasing  amounts  until  finally  extinguished  at  the 
conclusion  of  operations.  Interest  tables  show  that  the  annual 
payment  at  the  end  of  each  year  which  will,  at  the  date  of  last 
payment,  pay  this  debt  and  its  interest  at  6  per  cent,  to  that 
date — interest  being  compounded  annually  both  on  amounts 
paid  and  the  amounts  due— is  $193,248;  or  a  total  of  $1,545,984 
for  the  eight  payments.  This  is  equivalent  to  an  average  of  12.9 
cents  per  ton  of  ore  developed,  or  2.9  cents  per  ton  to  cover  only 
the  average  interest  charges.  (A  further  refinement  in  the  ap- 
portionment of  interest  charges  is  not  now  practical). 

The  complete  mining  cost  will  therefore  be  80  cents  plus  10 
cents  plus  2.9  cents,  or  a  total  of  92.9  cents  per  ton. 

Simply  from  the  foregoing  calculations  it  appears  that  the 
main  orebody  favors  extraction  by  underground  methods  rather 
than  by  shovels,  for  these  weighty  reasons;  first,  the  initial  ex- 
penditure which  must  be  made  before  full  production  can  be 
expected  is  only  a  little  more  than  one  third;  second,  the  time 
required  to  bring  the  property  up  to  production  is  two  years  in- 
stead of  three  years;  and  third,  the  calculated  cost  of  mining  is 
about  7  per  cent.  less. 

There  are,  however,  other  factors  which  must  be  considered 
before  re.aching  a  final  decision.  Some  of  these  will  now  be  taken 
up. 

Estimated  Grade  of  Ore  which  can  be  Worked  and  Yield  a 
Profit. — Certain  further  assumptions,  based  on  experimental 
work,  experience  and  current  practice,  must  here  be  made  and 
are  as  follows: 


Ratio  of  concentration  in  milling:  12  to  1 74  per  cent,  extraction 

Extraction  in  roasting,  smelting  and  converting ...   95  per  cent,  extraction 
Assumed  plant  recovery :  74  per  cent.  X  95  per  cent.  70  per  cent,  extraction 

Cost  of  coarse  crushing  at  mines $0.03  per  ton  of  ore 

Transportation  of  ore  to  mill 0.12  per  ton  of  ore 

Cost  of  concentrating 0.45  per  ton  of  ore 

Cost  of  roasting  or  nodulizing  concentrates . .     0.45  per  ton  of  concentrates 

Cost  of  smelting  concentrates. 2.00  per  ton  of  concentrates 

Cost  of  converting 8.00  per  ton  of  blister  copper 

Cost  of  freight,  refining,  selling  and  miscell.  .      0.016  per  Ib.  of  copper 

In  mining  low-grade  copper  ores  it  has  been  found  from  experi- 
ence that  the  average  per  cent,  of  copper  in  the  ore  mined  is 


204  STEAM  SHOVEL  MINING 

usually  lower  than  called  for  by  the  assay  plans.  This  is  partly 
due  to  mining  some  lower  grade  ore  than  at  first  contemplated, 
partly  to  intermixture  of  low-grade  capping  and  wall  rock  and 
partly  to  the  tendency  of  sampling  to  give  higher  rather  than 
lower  results.  For  these  reasons,  it  will  be  assumed  that  the 
grade  of  the  ore  will  be  lowered  by  5  per  cent,  or  to  an  average  of 
1.9  per  cent.,  if  mined  with  shovels;  and  by  10  per  cent.,  or  to 
an  average  of  1.8  per  cent.,  if  mined  by  the  branch-raise  method. 
It  will  be  safer  to  allow  no  increase  in  tonnage  expectancy  be- 
cause of  this  drop  in  grade. 

The  complete  mining,  treatment  and  marketing  costs  will  be 
as  follows: 

Cost  per  ton  of  ore 
By  shovels      By  underground 

Mining $1.00  $0.93 

Coarse  crushing 0. 03  0. 03 

Transportation  to  mill 0.12  0.12 

Concentration 0.45  0.45 

Roasting  or  nodulizing 0 . 04  0 . 04 

Smelting.' 0.17  0.17 

Total $1.81  $1 . 74 

The  copper  yield  per  ton  of  ore  will  be  70  per  cent,  of  38  Ib. 
or  26.6  Ib.  with]  shovel  [mining ;*and|70  per  cent,  of  36  Ib.  or 
25.2  Ib.  with  underground  mining.  The  production  cost  per 
pound  of  copper  will  then  be: 

Cost  per  pound  of  copper 
By  shovels     By  underground 

For  the  above  items 6.8  cents        6 . 9  cents 

For  converting 0.4  cents        0 . 4  cents 

For  freight,  refining,  selling,  etc 1.6  cents         1 . 6  cents 

Total 8.8  cents        8 . 9  cents 

Assuming  the  selling  price  of  copper  to  average  15  cents  per 
pound  over  the  life  of  operations,  and  2  cents  per  pound  to  remain 
fixed  as  the  cost  of  converting,  refining  and  marketing,  there  will 
be  left  13  cents  per  pound  from  which  to  pay  all  other  expenses 
and  profits.  As  the  expense  of  operations  using  shovel  mining 
is  $1.81  and  using  underground  mining  is  $1.74,  a  minimum  yield 
of  $1.81  -T-  0.13,  or  14  Ib.  for  the  former  and  $1.74  -f-  0.13,  or 
13.4  Ib.  for  the  latter,  is  required  to  meet  operating  expenses. 
With  a  plant  extraction  of  70  per  cent,  this  means  that  the  ore 
must  carry  20  Ib.  for  the  former  and  19.2  Ib.  for  the  latter,  or 


A  POWER  SHOVEL  MINE 


205 


assay  1  per  cent,  and  0.96  per  cent,  copper  respectively.  Con- 
sidering that  waste  admixture  and  other  reasons  mentioned 
may  reduce  the  grade  of  ore  shown  by  development  sampling  by 
5  per  cent,  for  shovel  mining,  and  10  per  cent,  for  underground 
mining,  the  grade  of  1.25  per  cent,  copper,  adopted  as  the  dividing 
line  between  ore  and  waste,  will  be  reduced  to  1.19  per  cent,  and 
1.12  per  cent,  as  against  the  grades  of  1.0  per  cent,  and  0.96  per 
cent,  respectively,  required  to  cover  operating  expenses,  or  to 
" break  even."  As  the  object  of  the  operations  is  to  show  a 
profit,  material  of  a  development  grade  of  1.25  per  cent,  (which 
should  show  a  profit  of  from  40  to  50  cents  per  ton)  is  con- 
sidered as  lean  as  should  be  sought.  As  a  further  refinement,  it 


ASSUMPTIONS: 


{lit              *i 
Stripping  COSTS  32  Cents  per  Cubic  Yard 
Mining  Costs  16  Cents  per  Ton 
Alt  ofner  Costs  to  Copper  Matte,  $1. 01  per  Ton  Ore 
Converting  and  Marketing  Cost,  2  Cents  per  Lb. 


Converting  and  Marketing  Cost,  2  Cents  per  Lb.  of  Copper 
\  Plant  Extraction  70  Per  Cent  Net  of  Copper  inOre  


NOTE' 


JNef  Prot it  per  Ton  Ore  of  Better  Grade  than  Base 2  2 
may  be  Estimated  by  Mu/ti ply  ing  Increase  in  Lb$ 
Coj>per  Content  by  70  Per  Cent  of  the  Selling  Price —  2.0 


I  or  Copper  Less  2  Cents. 


0.8  EXAMPLE! 

Let  Overburden*  2  Yds/To^ 


\  Let  Selling  Pric  e  of  Copper = 15  Cents  perLb 

Jo  Find  Grade  of  Ore  Required  to  Cover  Production  Cost-  Take  2  Yd. Curve  tol5tOrainah(I. 


Shows  0.99%  Copper  Required.  Again  Assume  2  Yds/Ton  ffatio-6rade  Ore,  1.5  Cu.Setling  Price 
0.2  IStperLb.  Then:  ToFind  Prof  it  per  Ton  Ore --Base  Ore  is  0.99% '  Cu.,Carrying 19.8 'li>.Ct/.;/.f%  Carries—  0.2 
0  \mb.;  Difference  Equals /0.2LbCiJ.  Prof  it  the* Equals  10.2x70%  x $0.13=  $0.93       \       \ 


10 


II 


13          14  15  16          17          15 

Selling  Price  of  Copper  in  Cents  per  Pound. 


19         20 


FIG.  45. — Chart  showing  approximate  yardage  of  overburden  a  ton  of  ore  of 
given  grade  can  carry,  with  given  selling  price  of  copper,  and  just  cover  complete 
production  costs. 

might  be  shown  that  the  plant  extractions  and  working  costs 
per  pound  of  copper  produced  will  be  less  favorable  the  further 
the  grade  of  the  ore  falls  below  the  average. 

To  quickly  determine  what  approximate  amounts  of  over- 
burden can  be  profitably  carried  by  various  grades  of  copper 
ore  and  under  various  metal  prices,  a  chart  similar  to  the  one 
shown  in  Fig.  45,  which  is  based  on  the  present  example,  may  be 
constructed.  A  similar  chart  may  also  be  used  for  underground 
mining  when  the  cost  of  such  mining  is  decided  upon.  Similar 
graphic  representations  may  be  drawn  for  other  classes  of  ore 


206  STEAM  SHOVEL  MINING 

and  will  be  found  approximately  correct  and  useful  for  the  operat- 
ing departments.  Obviously  the  higher  the  market  price  for 
metal,  or  the  lower  the  mining  and  treatment  cost  attainable,  the 
lower  will  be  the  grade  of  ore  possible  to  work  at  a  profit.  It 
should  be  remembered,  however,  that  the  plant  extraction  and 
production  cost  per  pound  will  be  less  favorable  as  the  grade 
falls. 

Consideration  of  Profits  from  Lower  Grade  Material. — The 
tonnage  estimate  showed  that  in  the  event  of  shovel  mining  a 
certain  tonnage  of  mixed  carbonate  and  sulphide  material  would 
be  removed  in  stripping  the  main  orebody;  also  that  another 
tonnage  of  low-grade  primary  sulphide  material  would  be  left 
stripped  below  the  main  orebody.  On  the  former  there  will 
be  no  mining  or  stripping  charge,  and  on  the  latter  a  mining 
charge,  but  no  interest  or  equipment  charge. 

Assuming  the  per  ton  treatment  costs  to  be  the  same  as  those 
estimated  for  the  main  orebody,  the  cost  of  working  the  copper- 
bearing  overlying  material  would  be  $1.00  per  ton  less  and  the 
cost  of  handling  the  underlying  material  would  be  say  $0.80 
less,  allowing  $0.20  per  ton  for  mining.  This  would  make  the 
corresponding  costs: 

$1.81  - 1.00,  or  $0.81  per  ton;  and  $1.81  -  0.80,  or  $1.01  per  ton. 
With  13  cents  net  to  cover  these  costs,  the  copper  yield  required 
is  0.81  -=-  0.13  =  6.2  lb.,  and  1.01  Vo.13  =  7.8  Ib.  respectively. 

Allowing  a  5  per  cent,  drop  in  the  development  grade  of  this 
material  there  would  be: 

600,000  tons  of  material  containing  1.09  per  cent.  Ciu  (equal  to  21.8  lb.  per 

ton) 
2,000,000  tons  of  material  containing  1.04  per  cent.  Cu.  (equal  to  20.8  lb. 

per  ton) 

Assuming  a  plant  extraction  of  60  per  cent,  on  this  mixed  and 
low  grade  material,  some  of  which  would  probably  have  to  be 
leached,  the  yield  per  ton  from  the  above  would  be  13.1  lb. 
for  the  former,  and  12.5  lb.  for  the  latter.  As  this  is  in 
excess  of  the  poundage  to  cover  actual  cost  requirements,  the 
profits  per  ton  would  be:  13.1  lb.  -  6.2  lb.  =  6.9  lb.  X  $0.13  = 
$0.897  for  the  carbonates.  12.5  lb.  -  7.8  lb.  =  4.7  lb.  X  0.13  = 
$0.611  for  the  sulphides. 

Under  these  conditions  it  is  indicated  that  this  material 
may  be  expected  to  yield  a  fair  profit,  and  that  material  assay- 


A  POWER  SHOVEL  MINE 


207 


ing  even  as  low  as  say  0.7  per  cent,  copper  might  be  handled 
without  loss  provided  it  bore  no  mining  or  stripping  charge. 

As  a  matter  of  proper  economic  policy,  a  plant  of  limited 
capacity  would  avoid,  if  possible,  the  treatment  of  such  material 
until  after  the  more  profitable  ore  had  been  exhausted. 

Comparative  Resume  of  Estimated  Profits  Derivable. — The 
above  discussion  may  now  be  summarized  as  follows: 


Profit  per  Ib. 

Yield  per  ton 

Profit 
per  ton 

Total  profit 

Main  ore  body: 

By  shovels: 

6.2  cents 

26.6  Ib. 

$1.65 

$19,800,000 

By  underground: 

6.1  cents 

25.2  Ib. 

$1.54 

$18,480,000 

Low  grade  carbonate: 

By  shovels: 

6.8  cents 

13.1  Ib. 

$0.90 

$540,000 

By  underground: 

(could  not 

be  mined  at 

a  profit) 

Low  grade  sulphide 

By  shovels: 

4.9  cents 

12.5  Ib. 

$0.61 

$1,220,000 

By  underground 

(could  not 

be  mined  at 

a  profit) 

1 

SUMMARY  OF  ALL  IMPORTANT  FACTORS 

By  shovels    By  underground 

Total  profit  derivable $21,560,000  $18,480,000 

Initial  capital  required $  3,000,000  $  1,200,000 

Time  required  to  reach  production 3  years             2  years 

Flexibility  of  efficient  output : 

Tonnage 50  per  cent.  25  per  cent. 

Grade limited  considerable 

Labor  force  required: 

Crew 325  men          500  men 

Percentage  of  total  operating  cost 45  per  cent.  60  per  cent. 

Availability — Ample  in  both  cases  but  fewer   high-priced  men  will  be 

required  with  shovels. 
Local  conditions: 

Climate — Generally  favorable;  open-pit  work  may  be  somewhat,  though 

not  seriously,  interfered  with  by  storms  for  three  months  of  the  year. 
Supplies — All   required   can  be  readily   secured  in  both  cases.     Of  the 

total  operating  cost,  supplies  will  amount  to  about  55  per  cent,  of 

steam-shovel  mining  and  40  per  cent,  for  underground  mining. 

Conclusion  and  Remarks. — In  consideration  of  the  foregoing 
estimates,  shovel  work  would  probably  be  recommended,  for 
although  much  more  initial  capital  is  required  and  a  longer  time 
will  elapse  before  arriving  at  full  production,  the  open-pit 
method  will  yield  larger  profits,  (even  omitting  the  doubtful 


208 


STEAM  SHOVEL  MINING 


carbonate  and  low  grade  sulphide  material),  have  greater 
flexibility  of  output,  deliver  a  cleaner  product,  give  a  higher 
percentage  of  the  tonnage  expectancy  and  be  subject  to  rather 
better  labor  conditions.  The  shovel  work  is  more  comprehensive 
and  there  is  more  assurance  of  the  correctness  of  the  observations. 
It  is  evident  that  the  work  is  of  sufficient  magnitude  to  fully 
justify  shovel  methods,  notwithstanding  the  attendant  heavy 
initial  expenditure. 

Although  the  example  chosen  is  one  of  a  low-grade  copper 
ore,  any  other  class  of  deposit,  such  as  a  body  of  iron  ore,  or  a 
coal  bed  or  vein,  may,  with  individual  modifications,  be  worked 
out  in  much  the  same  way. 


-350- 


->k- 200- >k- 


350' 


Area  Ore:  I00'x200'  =  20,000  Scj.'F 't*  1.0. 
"    Sfs:350'x350'=/Z^,500  «  "^^1-g^ 
«     D  :  250' x  200'=  50,000  "  "=f.5i?/~  ' 

FIG.  46. 

It  is  interesting  to  note  that  a  different  conclusion  might 
have  been  reached  had  the  ratio  of  overburden  to  ore  been  less 
favorable — say,  2J£  cu.  yd.  per  ton  of  ore — or  had  some  of  the 
other  factors  been  less  favorable  to  pit-mining.  Briefly,  such 
changes  will  be  further  illustrated. 

The  foregoing  example  may  be  considered  as  a  ''borderline" 
proposition,  and  it  was  especially  chosen  as  such  because  in  it 
could  be  brought  out  most  of  the  factors  that  must  eventually 
be  considered  in  the  solution  of  such  a  mining  problem.  Many 
problems  can  at  the  outset  be  quite  obviously  classified  as  under- 
ground or  shovel  propositions,  and  can  be  more  quickly  solved, 
since  many  of  the  minor  details  may  be  omitted. 

To  emphasize  this,  suppose  that  this  deposit  had  covered 
about  the  same  area  and  carried  about  the  same  tonnage  of  ore, 
but  that  its  principal  dimensions  had  been  much  different. 
For  example,  suppose  the  short  axis  or  width  had  been  200  ft. 
instead  of  1100  ft.;  the  long  axis  or  length,  8000  ft.  instead  of 


A  POWER  SHOVEL  MINE  209 

1800  ft.;  and  the  average  thickness  about  the  same,  or,  say,  100  ft. 
while  the  direct  overburden  remained  at  about  250  ft.  Under 
such  changed  conditions,  the  simple  section  herewith,  Fig.  46,  indi- 
cates something  like  8.6  cu.  yd.  of  overburden  per  cu.  yd.  of 
ore,  or,  say,  4.3  cu.  yd.  per  ton  of  ore.  Note  that  of  this  over- 
burden about  70  per  cent,  is  in  the  45°  side-slopes  alone, 
with  but  30  per  cent,  as  direct  overburden.  Thus  the  stripping 
cost  alone,  at  32  cents  per  cu.  yd.,  would  amount  to  $1.38  per 
ton  of  ore,  as  against  the  charge  of  $0.64  in  the  original  problem. 
While  the  solution  of  the  second  problem  is  not  precise,  it  is  quite 
close  enough  to  indicate  that  shovel  methods  need  not  be  given 
further  consideration. 

Now  consider  if  the  orebody  chosen  in  the  "border  line" 
illustration  had  been  simply  tipped  up  to  a  vertical  position  about 
either  of  its  axes,  and  then  covered  with  but  a  light  capping.  It 
will  be  seen  that  in  this  case  the  side-slope  overburden  represent- 
ing practically  100  per  cent,  of  the  total,  would  be  enormous, 
and  the  ratio  of  ore  to  overburden  such  as  to  decisively  prohibit 
open-pit  mining. 

Again,  had  both  the  average  thickness  of  the  orebody  and  the 
direct  capping  been  doubled,  the  final  ratio  of  overburden  to  ore 
would  have  been  much  less  favorable  than  in  the  first  case,  simply 
because  of  the  large  amount  of  side-slope  removal,  and  thus  the 
decision  would  have  been  against  shovel  methods.  On  the  other 
hand,  had  the  average  thickness  of  orebody  and  direct  over- 
burden been  halved,  the  ore-overburden  ratio  would  have  been 
more  favorable  to  shovel  work,  although  in  that  case  the  ratio  of 
output  and  the  initial  capital  investment  would  be  reconsidered 
for  downward  revision. 

Finally,  it  will  be  perfectly  obvious  that  had  all  other  conditions 
remained  the  same,  but  the  average  thickness  of  capping  been 
only  125  ft.  instead  of  about  250  ft.,  the  problem  would  have 
been  a  steam-shovel  one  without  any  question. 

SPECIAL  PROBLEMS 

There  are  some  special  problems  which  require  rather  a  differ- 
ent point  of  view  than  the  one  assumed  in  the  foregoing. 

1 1  not  infrequently  occurs,  especially  on  the  iron  ranges,  that  a 
deposit  is  found  which  must  be  analyzed  in  separate  parts  rather 
than  as  a  whole.  The  overburden  may  be  very  thick  over  one 

14 


210  STEAM  SHOVEL  MINING 

"part  but  thin  over  another  or  the  ore-overburden  ratio  may  vary 
widely.  Again,  the  shape  of  the  deposit  or  character  of  the  ore 
nlay  be  irregular.  Under  such  conditions,  a  combination  of 
methods,  open-pit  for  one  section  and  underground  for  another, 
may  be  much  more  advantageous  than  either  one  exclusively 
for  the  whole  deposit.  In  such  a  case,  a  careful  study  is  required 
"to  indicate  where  to  draw  the  dividing  line. 

In  shovel-mining,  a  certain  amount  of  ore  is  often  left  in  the 
side-slopes  that  could  not  be  economically  mined  by  any  method 
because  of  inaccessibility  or  lower  grade  than  the  average.  Such 
slope-ore  that  to  take  out  with  shovels  would  involve  the  removal 
of  too  great  an  additional  amount  of  overburden,  can,  however, 
often  be  profitably  mined  with  some  semi-underground  method 
carried  on  from  the  pit  bottom  or  benches. 

^West     /  s 

East 


vvvvvvvvv 
vvvvvvvvvvvv 
v  vvvvvvvvvvvvvvvvvvv 

FIG.  47. 


This  classification  of  ore  is  a  most  important  point  ;  its  recogni- 
tion and  application  extends  from  leaving  a  small  percentage 
of  the  total  orebody  as  "  fringe-ore"  in  the  pit  side-slopes  to 
segregating  the  entire  deposit  into  different  classes  of  ore  as 
regards  extraction.  To  illustrate  its  application  a  few  examples 
will  be  given. 

The  sketch,  Fig.  47,  is  a  rough  cross-section  of  an  ore  body 
which  contained  about  40  million  tons,  90  per  cent,  of  which 
could  be  mined  by  shovels  and  yet  keep  the  overburden-ore 
ratio  under  2  cu.  yd.  per  ton  of  ore.  In  most  places  the  ratio 
was  lighter  than  this,  but  where  it  was  found  to  be  heavier  for 
any  noteworthy  tonnage,  it  was  carefully  noted  by  a  different 
color.  Such  tonnages  were  found  to  lie  principally  in  the  side- 
slopes  as  indicated  in  the  sketch,  and  it  was  estimated  that  this 
ore  could  be  mined  by  slicing  or  caving  for  about  80  cents  per 
ton.  This  amount  was  about  the  same  as  the  cost  of  mining 
by  shovels  when  the  overburden-ore  ratio  did  not  exceed  four 


A  POWER  SHOVEL  MINE  211 

to  one.  A  simple  approximate  way  to  apply  this  dividing  ratio 
was  to  project  the  slope  line  through  the  ore  where  the  ratio 
did  not  exceed  four  in  waste  to  one  in  ore,  as  shown  on  the  west 
side  of  the  section.  In  this  way  it  was  found  that  there  were 
about  4  million  tons  of  ore  in  the  side-slopes  which  it  was  decided 
to  mine  by  semi-underground  methods.  It  may  be  mentioned 
that  to  have  lumped  this  side-slope  ore  in  with  the  rest  of  the 
orebody  would  have  given  an  overburden -ore  ratio  considerably 
lighter  than  four  to  one,  but  it  is  obvious  that  such  a  method 
is  not  fair  to  the  ore  more  favorably  situated,  and  would  have 
reduced  the  final  profits. 

A  second  illustration  is  given  in  Fig.  48,  where  60  per  cent, 
of  the  orebody  was  mined  by  shovels  and  40  per  cent,  by  slicing 
methods.  Here  the  overburden-ore  ratio  dividing  line  was 


y  v  v  v  ,V 

v  v  v    V 
BoVom.  v  ^  V  W  '. 


/Vvvvvvvvvvvvvv.vv  v*"v  v  v  v  v  v 
FIG.  48. 

drawn  at  IK  cu.  yd.  of  overburden  to  one  ton  of  ore,  it  being 
estimated  that  with  a  heavier  ratio  the  underground  method 
would  prove  more  economical. 

A  third  illustration  is  given  in  Fig.  49.  In  this  case  the  ore 
body  is  worked  by  open-cast  methods  which  will  be  continued 
until  the  constantly  increasing  side-slope  overburden  makes  it 
economically  necessary  to  adopt  another  method  of  mining.  It 
is  estimated  that  this  point  will  be  reached  when  the  overburden- 
ore  ratio  reaches,  say,  about  three  yards  of  overburden  to  one  ton 
of  ore.  This  will  not  be  entirely  caused  by  side-slopes,  but  also 
through  the  necessity  of  deepening  the  approach.  The  next 
method  will  probably  be  to  adopt  a  milling  system,  and  continue 
with  that  as  deep  as  the  side-walls  will  permit.  After  that,  it 
will  be  necessary  to  adopt  some  straight  underground  system, 
and,  on  account  of  the  character  of  the  ore  being  a  more  or  less 
massive  sulphide,  the  chamber-and-pillar  method  may  be 


212 


STEAM  SHOVEL  MINING 


adopted.  In  this  last  method,  the  worked-out  chambers  are 
closely  filled  with  waste,  just  as  compactly  as  possible,  before 
the  pillars  are  attacked;  the  object  being  to  avoid  too  much 
pressure  being  thrown  on  them,  as  in  that  event,  they  begin  to 
crush  and  heat  with  the  very  serious  danger  of  the  ore  catching 
fire.  It  is  expected  that  after  shovel  work  is  no  longer  practic- 
able, the  ore  will  be  hoisted  to  the  surface  through  a  shaft,  as  is 
roughly  indicated  on  the  sketch.  / 

From  this  illustration  it  will  be  seen  thatfin  the  case  of  a  long 
narrow  orebody,  or  a  steeply  pitching  one,  it  may  pay  better  to 
strip  and  mine  only  the  upper  portion  with  shovels^  because  so  to 
mine  below  a  certain  level  would  involve  the  removal  of  an 
excessive  amount  of  overburden  in  order  to  provide  safe  working 
slopes  or  trackage  spirals  of  reasonable  grade  to  haul  the  ore  out 


Shallow  Capping, 


Surface  Line . 


~ Li  mil-  "Open -Cast "Ore 
"L  imif  "Milling  "  Ore. 

"Underground  "Ore. 


FIG.  49. 


of  the  pit.  In  such  cases  (the\lower  portion  of  the  orebody  will 
be  at  least  partly  stripped^  and  it  may  often  be  possible  to 
continue  extraction  with  an  open-cast  milling  system.)  In  this 
system,  the  ore  in  the  pit  bottom  can  be  mined  into  a  checker- 
board series  of  mill-holes  feeding  into  a  net-work  of  underground 
extraction  drifts,  which  in  turn  connect  with  a  hoisting  shaft. 

In  some  cases  it  has  been  found  desirable  to  strip  an  orebody 
with  shovels,  or  drag-line  excavators,  and  then  mine  the  ore  by  a 
milling  or  underground  method.  Such  a  scheme  may  be  made 
desirable  where  the  overburden  consists  of  very  wet  material, 
such  as  quicksand,  resting  on  impervious  material  and  under 
such  conditions  that  the  orebody  cannot  be  properly  drained  for 
satisfactory  underground  mining.  Such  cases  were  seen  in  the 
Iron  ranges  of  Minnesota. 


A  POWER  SHOVEL  MINE  213 

It  was  previously  mentioned  that  certain  classes  of  material, 
such  as  large  bodies  of  massive  pyrites,  are  frequently  mined 
by  open-cast  methods  because  of  the  serious  fire  risk  involved 
in  mining  them  by  underground  methods.  In  this  case,  the 
comparative  direct  mining  costs  by  different  methods  may  be 
of  secondary  importance.  Examples  of  this  sort  will  be  found  at 
Rio  Tinto,  Spain. 

In  the  anthracite  coal  regions  of  Pennsylvania,  the  older 
methods  of  mining  were  generally  extremely  wasteful  of  the  coal. 
It  has  been  found,1  after  the  veins  had  been  mined  and  the  pillars 
then  robbed,  and  even  re-robbed,  that  from  75  per  cent,  to  50 
per  cent,  of  the  original  coal  had  been  left.  These  losses  were 
in  the  form  of  pillars,  neglected  portions  of  the  veins,  and  in 
abandoned  areas  due  to  "runs"  of  loose  material.  The  loss  by 
fire  has  also  been  considerable.  More  modern  practice  has 
reduced  these  losses  but  they  are  still  very  heavy.  Although 
the  problem  is  still  to  produce  the  largest  quantity  of  coal  for 
the  least  expenditure  of  money,  these  losses  have  caused  many 
operators  to  resort  to  stripping  operations.  This  method  may 
not  always  reduce  the  unit  cost  of  production  but  it  often  per- 
mits mining  a  much  larger  percentage  of  the  tonnage  and  in  a 
manner  so  much  more  comprehensive  that  a  higher  yield  of  pre- 
pared sizes  of  coal  is  obtained,  the  product  is  cleaner,  and  the 
output,  though  flexible,  may  be  kept  steady.  Furthermore, 
there  are  deposits  which,  because  of  the  way  they  have  been 
worked  in  the  past  or  because  of  the  loose  friable  character  of 
the  coal,  can  now  only  be  recovered  by  stripping  operations. 
In  such  cases  the  cost  may  be  considerably  higher  than  the 
usual  underground  cost.  Lessors  of  coal  lands  often  lower 
their  royalty  rates  in  order  to  induce  the  stripping  of  areas  that 
otherwise  would  remain  unmined.  In  addition  to  these  reasons 
for  stripping,  there  is  the  grave  question  of  the  conservation  of 
these  resources  and  when  so  considered,  wasteful  underground 
methods  are  generally  at  a  serious  disadvantage. 

Some  of  the  special  problems  will  be  further  considered  later. 

J.  B.  Warriner,  chairman  of  the  committee  representing  the 
larger  users  of  stripping  methods  in  the  anthracite  region,  gives 
two  illustrations  of  stripping  problems,  with  possible  fundamental 
errors  that  may  occur  in  preliminary  calculations. 

The  first  illustrates  the  economic  limits  of  stripping  in  area  and 

1  Warriner,  J.  B.?  Anthracite  stripping;  T.  A.  L  M.  E.,  Feb.,  1917,  pp.  33-60. 


214 


STEAM  SHOVEL  MINING 


depth.  It  is  assumed  that  it  has  been  decided  to  expend,  on 
coal  recovered  from  the  stripping  shown  in  Fig.  50,  an  amount 
per  ton  equal  to  the  average  margin  of  profit  of  the  colliery,  the 
return  on  the  investment  being  considered  to  be  secured  by  cer- 
tain factors  or  advantages  that  do  not  lend  themselves  readily 
to  calculation  in  exact  figures.  Then  this  cost  per  ton  figure 
is  translated  into  a  ratio  of  cubic  yards  of  overburden  removed 
per  ton  of  coal  uncovered,  and  amounts  for  example  to  2%  cu. 
yd.  per  ton.  Then  the  limits  in  area  and  depth  are  marked  out 
to  give  this  ratio.  These  limits  at  first  may  appear  satisfactory 
unless  the  problem  is  resolved  into  its  component  parts,  as  shown 
on  the  figure  by  the  shaded  areas.  Part  A  is  the  lowest  compo- 
nent part  which  comes  within  the  limits  of  the  ratio,  viz.,  2%  cu. 


Scale 


FIG.  50. — Anthracite  stripping  problem. 

yd.  per  ton  uncovered,  while  part  B  carries  3  cu.  yd.  and  C 
carries  3^  cu.  yd.  These  then  are  worked  at  a  loss,  regardless 
of  the  fact  that  parts  D  and  E  are  operated  at  a  considerable 
profit.  To  justify  the  removal  of  B  and  C  areas  there  must  be 
gained  some  marked  advantages  not  included  in  the  factors 
used  in  setting  the  2%-cu.  yd.  ratio;  otherwise  a  considerable 
amount  of  the  coal  reserve  would  be  depleted  at  no  profit. 

The  second  example,  illustrated  in  Fig.  51,  is  a  crop  stripping 
for  a  virgin  area  where  the  clay  and  gravel  overburden  must  either 
be  removed  or  a  chain  pillar  of  coal  left  below  the  surface  to  pre- 
vent the  contamination  of  the  prepared  coal.  In  this  case  it 
would  be  necessary  to  leave  a  60  ft.  chain  pillar  unless  it  is 
stripped.  The  coal  below  the  chain  pillar  can  be  mined  as 
cheaply  per  ton,  for  cutting  and  loading,  as  can  all  the  coal 


A  POWER  SHOVEL  MINE 


215 


from  gangway  to  surface  if  stripped.  By  the  latter  method, 
lower  unit  development  costs  would  be  obtained,  but  this  would 
amount  to  but  a  few  cents  per  ton  of  coal.  Against  assuming 
the  2%  to  1  ratio  as  the  economic  limit,  it  is  found  that  in  this 
case  there  are  4  cu.  yd.  to  1  ton  of  coal  in  the  chain  pillar,  and 


Surface 


B. 

Gangway'" 

FIG.  51. — Anthracite  stripping  problem. 

1  cu.  yd.  to  1  ton  of  coal  in  the  entire  area  between  gangway  and 
surface.  Therefore,  the  coal  that  can  properly  be  classed  as 
stripping  coal  is  mined  at  a  loss,  and  unless  there  are  other 
substantial  factors  in  its  favor,  the  stripping  should  not  be 
undertaken. 


CHAPTER  VII 
COST  OF  SHOVEL  WORK 

The  cost  of  excavating  and  disposing  of  material  worked  by 
shovels  is  subject  to  wide  variations  dependent  on  all  the  fac- 
tors previously  mentioned.  Examination  of  what  the  costs  have 
been  at  various  well  operated  properties,  taking  proper  account 
of  particular  local  conditions,  often  serves  as  a  useful  basis  in 
estimating  what  figures  may  be  expected  at  new  properties. 
It  is  to  be  noted  that  the  cost  of  labor  and  supplies  of  all  sorts 
has  a  decided  upward  tendency,  and  it  has  only  been  by  great 
improvement  in  methods,  equipment  and  general  coordination 
of  work  that  the  general  efficiency  has  been  increased  to  such 
an  extent  as  to  approximately  offset  the  higher  prices  paid  for 
labor  and  all  commodities.  What  has  been  done  in  the  past 
may  perhaps  be  expected  in  the  future,  although  it  now  seems 
probable  that  both  the  cost  of  production  and  the  selling  price 
of  the  commodity  produced  will  have  an  upward  tendency  in 
the  future  as  compared  with  pre-war  times.  In  examining  the 
following  examples  it  seems  fair  to  assume  that  shovel  costs  dur- 
ing the  years  1917  and  1918  were  abnormally  high,  owing  to 
general  war  conditions,  but  whether  such  costs  will  ever  again 
be  reduced  to  pre-war  figures  is  doubtful.  The  efficiency  of 
operating  labor  is  much  lower  when  the  men  are  new  at  their 
work  than  when  they  have  become  seasoned  to  it. 

As  illustrative  of  the  way  in  which  the  cost  of  open-pit  work 
has  risen  the  following  comparative  data  are  interesting. 

A  sliding  scale  was  adopted  depending  on  the  selling  price  of 
copper.  The  figures  given  here  are  for  copper  selling  at  18  to 
19  cents  per  lb.,  which  is  the  lowest  basis.  All  labor  received 
12%  cents  more  per  shift  for  each  increase  in  the  selling  price  of 
copper  of  1  cent  per  lb.  up  to  26  cents  per  lb.,  when  for  example, 
steam  shovel  engineers  would  receive  $7.83  per  shift.  Common 
labor,  however,  received  an  increase  of  7.5  cents  per  shift  per 

216 


COST  OF  SHOVEL  WORK  217 

1  cent  increase  in  selling  price  until  the  selling  price  reached 
22  cents,  thereafter  the  increase  was  at  the  rate  of  12.5  cents.  It 
has  been  found  that  labor  xjosts  represent  about  50  per  cent,  of 
the  total  cost  of  this  work. 


COMPARATIVE  WAGE  SCALE,  NEVADA  CONSOLIDATED  COPPER  COMPANY  PITS 

Occupation  Rate 

Summer,  19151        May,  19192 

Steam  shovel  engineers $6. 10  $6.83 

Steam,  shovel  cranemen 4.42  5. 16 

Steam  shovel  firemen 3 . 25  4 . 00 

Pitmen 2.30  2.95 

Locomotive  engineers 4 . 50  5 . 25 

Locomotive  firemen 3 . 25  4 . 00 

Locomotive  switchmen 3 . 50  4 . 25 

Yardmen 3.75  4.50 

Well  drillers 4. 10  4.85 

Tool  dressers 3.25  4.00 

Track  and  dump  men 2. 20  2.85 

Metalworkers 4.50  5.75 

Carpenters 4 . 75  5 . 75 

Bricklayers 6.00  7.25 

Electricians 5.25  6.00 

Mechanics'  helpers 3 . 25  4 . 50 

Common  labor,  American 3 . 00  4 . 25 

Common  labor,  foreign 2 . 20  2 . 75 


It  is  safe  to  say  that  the  cost  of  supplies  has  risen  in  1919  from 
25  to  50  per  cent,  higher  than  the  cost  in  1915.  Quoting  from 
the  1917  Chino  Copper  Company  report  the  general  manager 
states:  "In  1915,  $1.00  moved  2.83  cu.  yd.  of  material  in  place, 
in  1916,  2.63  cu.  yd.  of  material,  while  in  1917,  $1.00  moved 
only  1.97  cu.  yd.  Taking  1915  as  the  standard,  $1.00  moved  100 
per  cent,  in  1915,  it  moved  92.93  per  cent,  in  1916,  and  only 
69.61  per  cent,  in  1917.  In  stating  the  above  costs,  taxes, 
other  administrative  and  general  charges  have  been  included  as 
usual."  The  experience  of  other  companies  no  doubt  closely 
parallels  that  of  the  Chino  Company. 

1  In  1915  the  shift  was  nine  hours  and  straight  time  was  paid  for  all 
overtime. 

2  All  wages  in  1919  based  on  eight  hours. 


218 


STEAM  SHOVEL  MINING 


EXAMPLES  OF  COSTS 

NEVADA  CONSOLIDATED  COPPER  Co.,  RUTH,  NEVADA 


Year 

Cu.  yd.  over- 
burden  removed 

Cost  per 
cu.  yd. 

Tons  of  ore 
removed 

Cost  per 
ton 

1911  and  previous 

6,038,683 

$.3630 

7,137,416 

$0.157 

1912 

2,732,976 

.3364 

2,596,991 

0.1735 

1913 

3,100,661 

.3399 

2,889,389 

0.1775 

1914 

3,044,966 

.3171 

2,513,241 

0.1517 

1915 

2,758,350 

.2887 

2,991,782 

0.1524 

1916 

3,988,650 

.3009 

3,337,570 

0.2370 

1917 

2,998,025 

.3443 

3,076,285 

0.3338 

1918 

2,617,771 

.4120 

2,711,743 

0.4169 

Totals  to  Jan.  1,  1919:  27,280,088  cu.  yd.  of  waste  and  26,855,857  tons 
of  ore  had  been  removed. 

Under  the  cost  of  overburden  are  included  all  charges  complete 
to  waste  dumps. 

Under  the  cost  of  ore  are  included  all  charges  such  as  labor, 
supplies,  repairs,  management,  proportion  of  general  and  New 
York  expense,  etc.,  and  taxes.  Transportation  of  ore  from  the 
assembly  yards  to  the  mills  is,  of  course,  excluded.  The  item 
of  taxes  alone  amounted  to  4.08  cents  in  1915;  11.28  cents  in 
1916;  14.48  cents  in  1917,  and  15.81  cents  in  1918.  This  charge 
is  entirely  arbitrary  and  beyond  the  control  of  mining  operation. 
The  figures  are  taken  from  the  annual  reports  of  the  company. 
One  cubic  yard  is  equivalent  to  2.16  tons. 

The  stripping  cost  may  be  analyzed  approximately  as  follows: 


Steam  shovel  operation: 

Shovel  labor 

Fuel 

Supplies  and  repairs . 
Pit  labor.. 


Cost  per  cu.  yd.  Cost  per  cu.  yd. 


$0.014 
0.010 
0.010 
0.011 


$0.045 


Locomotive  haulage  and  train  crew  service: 

Locomotive  labor 

Fuel 

Supplies  and  repairs 

Yard  and  train  crews 

Dump  labor 

Track  maintenance 

Car  repairs 


0.025 
0.030 
0.003 
0.006 
0.025 
0.025 
0.015 


$0.129 


COST  OF  SHOVEL  WORK  219 

Supervision: 

Superintendents  and  foremen 0 . 005 

Engineering 0.002 

$0.007 
Drilling  and  blasting : 

Churn  drills. 0.015 

Labor 0.006 

Explosives 0 . 066 

$0.087 
General  and  miscellaneous: 

Water  supply 0.005 

Building  repairs  and  miscel 0 . 003 

Fund  for  renewal  reserve 0 . 030 

General  expense  and  insurance 0.010 

$0.048 
Total  per  cubic  yard  in  place  $0 . 316 

The  mining  cost  may  be  analyzed  approximately  as  follows: 

Cost  per  ton         Cost  per  ton 

Breaking  ore: 

Churn  drills $0.007 

Labor 0. 003 

Explosives 0.033 

$0.043 

Steam  shovel  operation: 

Shovel  labor 0.008 

Fuel 0.006 

Supplies  and  repairs 0 . 006 

Pit  labor 0.007 

$0.027 

Locomotive  haulage  and  train  crew  service: 

Locomotive  labor 0. 008 

Fuel 0.010 

Supplies  and  repairs 0 . 002 

Yard  and  train  crews 0 . 002 

Track  maintenance 0 . Oil 

Car  repairs 

$0.033 

General  and  miscellaneous : 

Water  supply 0. 003 

Supervision  and  engineering 0 . 006 

Building  repairs  and  miscel 0 . 003 

Renewals  reserve  fund 0.015 

Pit-pumping 0 . 002 

General  expense  and  insurance 0. Oil 

$0.040 

Total  mining  cost  per  ton $0. 143 


220 


STEAM  SHOVEL  MINING 


To  this  must  be  added  government  taxes  as  mentioned  in  the 
foregoing.  The  ore  is  also  charged  with  a  certain  amount  per 
ton  for  the  redemption  of  prepaid  stripping.  The  cost  of  trans- 
portation of  ore  to  mills  is,  of  course,  carried  separately. 

The  coal  consumed  per  steam  shovel  shift  and  per  locomotive 
shift  ran  about  2.15  and  2.5  tons  respectively;  as  the  pit  deep- 
ened the  figure  for  locomotives  has  increased  by  about  2.2 
tons.  An  average  of  about  1000  cu.  yd.  per  shovel  shift  and 
500  cu.  yd.  per  locomotive  shift  were  moved.  About  60  tons 
of  ore  and  35  cu.  yd.  of  waste  were  broken  per  foot  of  churn 
drill  hole  shot.  About  20  Ib.  of  coal  were  consumed  per  foot  of 
hole  drilled.  The  powder  consumption  was  about  0.28  Ib.  per 
ton  of  ore  and  0.55  Ib.  per  cu.  yd.  of  waste.  Elimination  of  the 
black  powder  earlier  used  on  waste,  materially  reduced  the 
quantity  required  per  cu.  yd.  of  waste  and  it  was  found  ad- 
vantageous to  use  Trojan  powder  for  all  classes  of  material. 
Using  about  50  per  cent,  cheap  black  powder  and  50  per  cent,  of 
a  40  per  cent,  powder,  the  consumption  per  cu.  yd.  of  waste 
was  about  0.75  Ib.  per  cu.  yd.  About  3  gal.  of  lubricating  oil 
and  1.5  Ib.  of  grease  were  consumed  per  1000  cu.  yd.  of  material 
moved. 

UTAH  COPPER  COMPANY,  BINGHAM,  UTAH 


Year 

Cu.  yd.  over- 
aurden   removed 

Cost'  per 
cu.  yd. 

Tons  concentrat- 
ing ore  removed 

Cost  per 
ton 

Prior  to  1910 

4,347,810 

1910 

2,814,746 

SO.  40 

4,340,245 

$0.2767 

1911 

5,450,604 

0.371 

4,680,801 

0.2461 

1912 

4,676,568 

0.376 

5,315,321 

0.2635 

1913 

4,835,479 

0.425 

7,519,392 

0.2094 

1914 

5,708,836 

0.368 

6,470,166 

0.2262 

1915 

5,961,367 

0.285 

8,494,300 

0.1661 

1916 

5,911,455 

0.291 

10,994,000 

0.2024 

1917 

4,271,868 

0.372 

12,542,000 

0.3688 

1918 

4,064,091 

0.468 

12,160,700 

0.4285 

.  Totals  to  Jan.  1,  1919:  48,042,824  cu.  yd.,  of  overburden  (covering 
258.67  acres,  of  which  132.16  acres  had  been  completely  stripped)  and  79,- 
381,400  tons  of  ore  had  been  removed. 

Under  the  cost  of  overburden  are  included  all  charges  complete 
to  waste  dumps. 

Under  the  cost  of  ore  are  included  all  general  and  tax  charges, 
but  not  the  proportion  of  stripping  or  development  charges. 


COST  OF  SHOVEL  WORK 


221 


The  tax  charges  were  high  in  1917  and  1918  as  also  were  labor  and 
supplies.  Stripping  costs  have  been  charged  off  on  the  basis  of 
7J^  cents  per  ton  of  ore  mined,  it  being  estimated  that  appro- 
ximately four  tons  of  ore  would  eventually  be  mined  for  each  cu. 
yd.  of  overburden  removed.  An  average  of  about  0.8  cent  per 
ton  has  been  charged  as  the  cost  of  development  of  the  ore. 
The  above  .figures  are  taken  from  the  annual  reports  of  the 
company. 
The  stripping  cost  may  be  divided  up  approximately  as  follows : 

Cost  per  cu.  yd. 

Drilling  and  blasting $0 . 085 

Steam  shovel  operations 0 . 095 

Locomotive  haulage  and  dump  labor 0 . 085 

Track  maintenance 0 . 080 

Dump  car  repairs 0 . 015 

Overhead'  expense 0 . 010 

General  mine  charges 0. 010 

.  Freight 0.020 


Total  per  cu.  yd.  in  place $0. 400 

The  mining  cost  may  be  divided  up  approximately  as  follows: 


Drilling  and  blasting .... 
Steam,  shovel  operations. 


Cost  per  ton 

$0.050 

0.055 

Locomotive  haulage 0. 055 

Track  maintenance 0 . 025 

Overhead  expense  at  mine 0 . 005 

General  mine  charges 0 . 020 

General  office,  administration   and  insurance..  0.015 

Total  mining  cost  per  ton $0 . 225 

To  this  government  taxes  must  be  added;  these  are  widely 
variable  but  approximate  7.5  cents  per  ton.     As  mentioned,  7.5 
cents  per  ton  is  charged  for  redemption  of  prepaid  stripping. 
CHINO  COPPER  COMPANY,  SANTA  RITA,  NEW  MEXICO 


Year 

Cu.  yd.  over- 
burden   removed 

Cost  per 
cu.  yd. 

Tons  ore 
removed 

Cost  per 
ton 

1911  and  previous 

2,000,000 

$0.3168 

600,000  + 

$0.15  + 

1912 

2,223,678 

0.2761 

1,301,463 

0.1652 

1913 

3,082,174 

0.3343 

1,976,572 

0.2313 

1914 

3,173,717 

0.3347 

2,114,910 

0.2213 

1915 

3,133,916       '  0.3428 

2,600,271 

0.1947 

1916 

3,564,623          0.3882 

3,216,065 

0.1988 

1917 

3,712,414 

0.3710 

3,607,825 

0.41± 

1918 

3,264,556          0.51  + 

3,749,238 

0.51  + 

222 


STEAM  SHOVEL  MINING 


Totals   to   Jan.    1,   1919:  23,863,755    cu.    yd.    of   waste   and 
18,943,755  tons  of  ore  have  been  removed. 

The  costs  for  1915  may  be  analyzed  about  as  follows: 


- 

Mining  cost  pe.r  ton 

Labor 

Supplies 

Total 

Crushing  at  mine  (^  of  ore)  
Drilling                                             .  .      

0.75cts 
0.80 
0.25 
4.25 
4.25 

0.25cts 
0.20 
1.50 
2.25 
2.50 

l.OOcts 
1.  00 
1.75 
6.50 
6.75 

Blasting 

Hauling                           

Loading                                                     

Administration  

lO.SOcts 

6.70cts 

17.00cts 
2.50 

19.50cts 

Total  mining  cost  per  ton  

Labor 

Supplies 

Total 

Drilling 

1  40cts 

0  40cts 

1  80cts 

Blasting  
Loading  ... 

0.40 
7  00 

3.60 
4  20 

4.00 
11  20 

Hauling 

9  50 

3  50 

13  00 

Administration  

18.30 

11.70 

30.00 
5  00 

Total  cost  per  cu.  yd  .  '.  . 

35  OOcts 

Under  the  cost  of  overburden  are  included  all  charges  to  waste 
dumps. 

Under  the  cost  of  ore  are  included  a  proper  apportionment  of 
fixed  and  general  charges  of  all  kinds.  The  high  costs.in  1913  and 
1914  were  due  largely  to  the  limited  areas  and  inconvenient  or 
intermittent  way  in  which  the  ore  shovels  had  to  operate.  They 
had  to  avoid  interference  with  the  stripping  shovels,  and  the 
standard  railroad  ore  car  service  was  not  as  steady  or  effective  as 
was  the  dump  car  service  supplying  the  stripping  shovels. 
Furthermore  the  ore  shovels  were  often  held  up  awaiting  the 
breaking  of  large  pieces  so  that  oversize  material  would  not  be 


COST  OF  SHOVEL  WORK  223 

delivered  to  the  mill.  The  stripping  shovels  often  avoided 
much  of  this  delay.  Larger  working  areas  and  the  installation 
of  a  primary  crusher  at  the  mine  did  away  with  many  delays  and 
inconveniences  and  resulted  in  the  delivery  of  a  more  uniform 
character  of  ore  and  better  all  round  operating  economies.  The 
high  costs  in  1917  and  1918  are  again  due  to  war  conditions  and 
taxes.  One  cu.  yd.  is  equal  to  about  1.95  tons.  The  figures  are 
taken  from  the  annual  reports  of  the  company. 

Stripping  costs  are  charged  to  operations  on  the  basis  of  30 
cents  per  ton  of  ore  mined. 

CHILE  COPPER  COMPANY,  CHUQUICAMATA,  CHILE 

The  mining  costs  at  this  property  -in  1919  were  as  follows:  (Tons  here 
are  metric  tons  of  2204  Ibs.) 

Cost  per  ton 
shipped 

Breaking  ground $0 . 148 

Shovel  operation 0 . 143 

Breaking  ground  in  front  of  shovels 0 . 033 

Tramming : 0 . 114 

Sampling  and  assaying 0 . 007 

Supervision 0 . 009 


Total $0.454 

Both  oil  and  coal  were  used  for  firing  shovels  during  this  period. 
Electric  power  at  the  mines  costs  about  1J£  cents  per  KWH  and 
the  consumption  is  about  0.4  KWH  per  ton  of  material  loaded  by 
electric  shovels.  About  \Y±  Ibs.  of  oil  is  buined  per  KWH. 
Oil  costs  about  $24.00  per  ton  at  the  mine  and  is  more  econom- 
ical than  coal.  Coal  costs  about  $30.00  per  ton  and  7.6  Ib.  of 
coal  is  consumed  per  ton  of  material  loaded.  Rating  coal  at 
$40.00  per  ton  and  electric  power  at  2  cents  per  KWH,  a  saving 
of  about  8  cents  per  ton  was  effected  by  the  use  of  electric  shovels. 

Blasting  is  done  both  by  churn  drill  holes  and  tunnelling  as 
explained  in  Chap.  IV. 

The  distribution  of  shovel  time  ran  about  as  follows : 

Loading,  Repairs,  Blasting,  Waiting  for  cars,  Other  delays, 

per  cent.  per  cent.  per  cent.  per  cent.  per  cent. 

27  13  8  17  35 

The  locomotives  used  were  both  coal  and  oil  burners,  the  former 
consuming  about  1.8  metric  tons  of  coal  per  shift  and  the  latter 
one -half  as  much  as  the  oil,  although  the  oil  contained  about 


224  STEAM  SHOVEL  MINING 

18,000  B.t.u.  per  Ib.  as  against  13,000  B.t.u.  for  the  coal. 
The  locomotive  service  distribution  was  about  as  follows : 

Shovel  Coaling  and  Taking        Yard       Round      Idle  in    Waiting  for   With   Miscellaneous 
service,        oiling,       water,       service,      house,        yard,        empties,      crane,        services, 
per  cent,    per  cent,  per  cent,  per  cent,  per  cent,  per  cent,   per  cent,  per  cent,     per  cent. 

60  2          1.3         3.6         8.8         6.5  3  2  11 

The  cost  of  explosives  per  ton  of  material  broken  was  about  6 
cents,  black  powder  costing  6  cents  per  Ib.  and  40  per  cent, 
dynamite,  26  cents  per  Ib.  Only  about  2  per  cent,  of  the 
charge  consisted  of  the  latter. 

Mesabi  Iron  Ore. — Usual  stripping  costs  on  the  iron  ranges 
vary  from  15  cents  to  30  cents  per  cu.  yd.,  depending  largely 
on  the  size  of  the  job,  local  operating  conditions  and  class  of 
equipment  employed.  Contract  prices  for  such  work  have  usu- 
ally been  let  at  from  25  to  32  cents  per  cu.  yd.  on  jobs  carrying 
one  half  million  cu.  yd.  or  more.  The  cost  sheets  covering  such 
work  show  a  range  of  from  14  to  20  cents  per  cu.  yd.  under  favor- 
able conditions  and  from  20  to  26  cents  per  cu.  yd.,  or  even 
higher,  under  unfavorable  conditions.  In  winter  weather  these 
costs  may  be  increased  by  from  5  to  6  cents  per  cu.  yd.  To  this 
must  be  added  the  interest  charges  on  the  capital  investment 
tied  up  in  prepaid  stripping.  For  example,  a  40  acre  tract  may 
require  stripping  to  a  depth  of  100  ft.  costing  from  $1,250,000  to 
$2,000,000  and  covering  a  period  of  3  years  to  complete.  As- 
suming the  annual  interest  charge  to  be  $100,000,  charged  against 
eight  million  tons  of  ore,  to  be  mined  at  the  rate  of  one  million 
tons  per  year,  the  stripping  charge  would  be  about  25  cents  per 
ton  of  ore,  which  must  be  added  to  the  mining  cost. 

Some  of  the  more  favorably  situated  properties  show  a  cost  of 
ore  on  the  cars,  including  stripping,  mining  and  local  overhead 
charges,  of  from  15  to  18  cents  per  ton. 

The  cost  of  mining  ore  varies  principally  with  the  hardness, 
amount  of  rock  sorting  required,  regularity  of  iron  and  phos- 
phorus content,  and  transportation  charge.  Taking  the  Mesabi 
as  a  whole,  the  cost  of  open-pit  ore  on  the  cars  varies  from  15 
to  75  cents  per  ton  under  very  favorable  and  very  unfavorable 
conditions  respectively.  This  cost  includes  all  local  and  outside 
overhead  charges  including  stripping,  but  not  royalty  or  interest 
on  fee  investment.  The  average  mining  cost  of  central  Mesabi 


COST  OF  SHOVEL  WORK  225 

open-pit  ores  loaded  on  cars  will  fall  within  40  cents  per  ton  under 
average  conditions  and  within  30  cents  per  ton  under  favorable 
conditions.  The  ores  from  the  Mahoning-Hull-Rust  orebody 
are  exceptionally  favorably  situated  as  the  deposit  is  very  large, 
the  stripping  is  light  and  the  operating  conditions  are  very  good. 
The  cost  here,  shipping  about  35,000  tons  per  day,  is  about  15 
cents  per  ton,  of  which  less  than  10  cents  is  for  direct  mining. 
Including  these  ores  the  average  cost  of  mining  the  central  two 
thirds  of  the  open-pit  Mesabi  ores  will  average  about  30  cents  per 
ton,  of  which  about  15  cents  may  be  taken  for  the  cost  of  remov- 
ing overburden  and  15  cents  as  the  cost  of  shovel  mining  includ- 
ing bringing  cars  into  the  pit,  loading  them  and  returning  them 
to  the  yards.  As  compared  with  earlier  hand-loading  work, 
the  shovel  loads  at  from  ^o  to  J^o  the  cost.  This  is  under  good 
operating  conditions;  under  very  adverse  conditions  hand-load- 
ing has  actually  at  times  been  cheaper. 

The  shovel  crews  from  8  to  10  men  as  follows:1 

1  runner,  wages $5.77  per  10-hr,  day.     Bonus  $25.  for  26  days. 

1  craneman,  wages 4.04  per  10-hr,  day.     Bonus  $20.  for  25  days. 

1  fireman,  wages 2.50  per  10-hr,  day. 

4  to  7  pitmen,  wages 2.35  per  10-hr,  day. 

Locomotive  engineers  were  paid  $4.10  per  10-hr,  day  with  a 
$20  maximum  bonus  for  continuous  good  work  for  the  month. 
The  direct  labor  cost  at  the  shovel  runs  from  $23.45  to  $30.50 
per  day,  assuming  full  bonus  is  paid. 

The  shovel  supplies  run  about  as  follows : 

Coal — 2>£  to  3>£  tons  per  10-hr,  shift. 

Lubricants— black  oil  5  gal.,  cylinder  oil  5  gal.  per  24  hrs. 

IHuminants — gasoline  10  to  15  gal.  per  night;  kerosene  2><j  gal.  per  night. 

'Water — 12,000  to  15,000  gal.  per  24  hrs. 

Much  of  the  ore  of  the  Lake  Superior  region  is  mined  on  lease 
with  royalties  ranging  from  10  cents  to  $1.35  per  ton.  The 
average  for  the  region  is  between  30  and  50  cents,  the  higher  fig- 
ures appearing  in  later  leases.  The  Mesabi  range  bears  the  high- 
est general  average  of  royalties,  viz.,  from  25  cents  to  $1.00  per 
ton.  The  royalty  rate  is  a  measure  of  the  value  of  the  ore  in 
the  ground  to  the  fee  owner,  who  generally  demands  as  high  a 
price  as  the  leasor  can  afford  to  pay.  The  higher  the  grade  of 
the  ore  and  the  lower  the  mining  and  transportation  cost,  the 

1  These  were  the  conditions  in  the  middle  of  1915. 

15 


226  STEAM  SHOVEL  MINING 

higher  will  be  the  royalty.  The  Minnesota  State  Tax  Com- 
mission for  1915  valued  the  ores  for  the  purpose  of  taxation  at 
an  average  of  18  cents  per  ton,  viz.,  50  per  cent,  of  what  was 
regarded  as  the  real  present  value  (36  cents  per  ton)  of  the  ore 
in  the  ground. 

Miscellaneous  Work.  Granby  Mine,  Phoenix,  B.  C. — A 
Bucyrus  40  R.  electric  shovel  started  at  this  property  in  1914, 
handled  about  500,000  tons  of  material  at  a  cost  of  about  45  cents 
per  ton.  The  conditions  of  mining  were  rather  difficult. 

An  Ontario  hydro-electric  canal  job,  involving  the  removal  of 
about  eleven  million  cu.  yd.  of  earth  and  four  million  cu.  yd.  of 
rock,  removed  the  former  for  about  23  cents  per  cu.  yd.  com- 
plete. Electric  shovels,  of  the  225  B  Bucyrus  make,  were  used 
and  power  cost  about  %  per  cent.  KWH.  The  cut  averaged 
about  160  ft.  at  the  top,  84  feet  at  the  water  line  and  50  ft.  in 
width  at  the  bottom.  Below  this  came  rock,  which  was  taken 
out  in  box  cut  with  other  shovels  of  the  110-ton  R.  R.  type.  The 
waste  was  hauled  about  2J£  miles. 

Anthracite  Strippings. — The  following  is  quoted  from  a  paper  by 
Mr.  J.  B.  Warriner.1 

"Anthracite  strippings  are  a  notable  example  of  the  way  in  which 
labor-saving  devices  have  held  down  operating  costs  in  the  face  of 
steadily  advancing  labor  costs.  In  the  early  day  when  $1.10  was  the 
regular  wage  for  a  10-hr,  day,  unit  stripping  costs  were  around  $0.26 
per  cu.  yd.  for  clay  excavation  and  $0.60  for  rock.  With  present 
wages  nearly  double  the  early  rate,  stripping  costs  range  from  $0.16  to 
$0.20  for  clay  and  from  $0.35  to  $0.40  for  rock.  This  is  due  largely  to 
the  use  of  steam  shovels  and  the  increase  in  the  size  of  the  shovels  em- 
ployed." 

Further  on,  in  speaking  of  the  ability  of  large  drag-line  excava- 
tors to  do  this  work  more  cheaply  than  shovels,  it  is  stated: 
"  Whenever  it  is  possible  to  cast  the  excavated  material  to  one 
side,  rather  than  to  load  it  into  cars,  labor  is  largely  dispensed 
with.  The  labor  item  in  ordinary  strippings  is  probably  70  per 
cent,  of  the  total  cost  of  stripping,  but  in  such  an  operation  as 
described  this  percentage  is  reduced  to  about  50  per  cent.  From 
the  results  obtained  to  date  it  is  believed  that  present  stripping 
costs  can  be  reduced  by  these  advanced  methods  by  at  least  10 
cents  per  cu.  yd.,  allowing  amply  for  interest  and  deprecia- 

1  T.  A.  I.  M.  E.  Anthracite  Stripping.     N.  Y.  Meeting,  Feb.,  1917. 


COST  OF  SHOVEL  WORK  227 

tion  items.  The  cost  for  power  has  been  proven  to  be  only  1 
cent  per  cu.  yd.  and  the  first  cost  of  the  equipment  is  little  greater 
than  for  an  ordinary  70-ton  shovel  operation  requiring  a  full 
complement  of  locomotives,  dump  cars,  rails,  etc.  The  principal 
item  of  cost  is  the  moving  of  so  large  a  machine  from  one  strip- 
ping operation  to  another,  or  to  and  from  the  railroad."  It  was 
evidently  the  intention  that  these  machines  would  be  used  on  the 
clay  strippings  but  not  on  the  rock  work. 

Brown-coal  Mining  in  Germany. — The  estimated  cost  of  re- 
moving overburden  is  from  6  to  10  cents  per  cu.  yd.,  and  of 
mining  open-pit  coal  deposits  (not  including  stripping  charge), 
of  from  25  to  60  ft.  thick,  from  9  to  10  cents  per  short  ton.  The 
stripping  is  done  with  continuous-bucket  excavators  previously 
described,  and  the  coal  is  mined  by  the  milling  system.  In  1913 
about  87,000,000  tons  of  this  coal  were  mined. 

Yukon  Gold  Company. — In  providing  a  seventy  mile  conduit 
for  the  water-supply  for  the  Klondike  hydraulic  mines1  of  the 
Yukon  Gold  Company,  37  miles  of  open  ditch  was  constructed. 
The  top  layer  of  ground  is  frozen  <fmuck"  composed  of  very  fine 
black  silt  and  ice,  frozen  .to  a  depth  of  from  nothing  to  several 
hundred  feet.  This  is  overlain  by  a  blanket  of  moss  often  a  foot 
or  more  in  thickness,  which  has  the  effect  of  preserving  the  muck 
in  frozen  condition  throughout  the  year.  Thirty  miles  of  the  open 
ditch  was  dug  with  six  30-ton  steam  shovels,  the  remainder  with 
horse  scrapers.  As  the  shovels  required  a  working  space  at  least 
16  ft.  wide,  no  side-sloping  was  done  with  them.  Small  quanti- 
ties of  frozen  material  were  removed  with  40  per  cent,  dynamite, 
but  the  larger  patches  were  passed  over,  and  after  thawing  were 
taken  out  with  scrapers.  The  shovels  worked  two  10-hr,  shifts 
and  burned  about  three  cords  of  wood  per  day.  The  record  per- 
formance for  one  shift  was  410  lineal  feet  of  ditch  or  1200  cu.  yd., 
and  the  average  performance  was  14.7  lineal  feet  or  51  cu.  yd. 
per  working  hour,  equivalent  to  11.2  lineal  feet  or  38.7  cu..yd. 
per  available  hour.  The  season  lasted  from  June  15  to  about 
October  15,  with  work  usually  slow  the  first  and  last  weeks, 
100  working  days  being  about  the  true  season  length.  The  actual 
cost  per  lineal  foot  was  about  the  same  for  shovel  as  for  scraper 
work,  but  the  scarcity  of  horses  would  have  greatly  delayed  the 
work  had  they  been  used  exclusively  and  it  would  have  been 
expensive  to  import  them.  The  cost  of  this  excavation  was  some- 

1  H.  H.  Hall,  M.  &  S.  P.,  Aug.  28,  1915. 


228  STEAM  SHOVEL  MINING 

times  as  great  as  $5  per  cu.  yd.  Common  labor  was  paid  $4 
per  day  and  board,  and  horses  were  hired  at  $100  per  month 
including  found. 

Panama  Canal. — The  Canal  Records  of  Nov.  8,  1911,  and  Feb. 
7,  May  8  and  Aug.  7,  1912,  Parts  II,  give  the  cubic  yards  ex- 
cavated and  the  costs  per  cu.  yd.  of  steam  shovel  work  in  the 
Central  Division  for  the  four  quarters  of  the  fiscal  year  ending 
June  30,  1912:  From  these  figures  the  average  costs  for  the  year 
have  been  calculated  as  follows: 

Cost  per  cu.  yd., 
cents 

Drilling 5 . 36 

Blasting 6.22 

Loading , .  4 . 92 

Tracks ' 8 . 85 

Transportation 7.34 

Dumps 4.78 

Pumps '.  0.41 

Maintenance  of  equipment 8 . 43 

Plant  arbitrary 3 . 94 

Division  expense 1 . 45 

Administration . .  3 . 64 


Total 55.34 

Quantity  excavated 16,917,662  cu.  yd. 

Keeping  of  Cost  Records.  Graphic  Records. — Graphic  repre- 
sentation showing  the  efficiency  of  shovel  operations  is  always 
found  helpful  to  the  operating  officials  and  to  the  crews.  Such 
representation  is  more  easily  understood  than  lists  of  figures  by 
these  men,  and  it  is  always  to  be  encouraged.  Auditing  is  a 
matter  of  past  history,  but  when  the  results  are  clearly  presented 
and  can  be  followed  from  day  to  day,  there  is  sure  to  be  developed 
an  incentive  for  improvement.  In  addition  to  production  and 
service  records,  some  empirical  cost  graphs  were  worked  out1 
for  the  Nevada  Consolidated  to  show  the  effect  of  varying  daily 
production  on  cost.  Figs.  52,  53,  54  and  55  illustrate  the  method, 
and  by  the  use  of  such  charts  a  daily  unit  cost  of  production 
can  be  figured  to  a  fraction  of  a  cent.  The  operating  costs  are 
classified  under  indirect  or  overhead  expense,  shovel-operating 
expense  and  locomotive-operating  expense.  To  illustrate  the  use 
of  the  charts  assume  that  six  shovels,  each  operating  two  shifts, 
handle  in  24  hr.  a  total  of  12,000  cu.  yd.  of  material,  or  an  aver- 

1  J.  M.  Anderson,  E.  &  M.  J.,  Jan.  27,  1917. 


COST  OF  SHOVEL  WORK 


229 


UNIT  OF 
PRODUCTION   15 

YARDAGE 

EFFICIENCY  .BASED 

ON  COST  PER 

CUBIC  YARD 


FIG.  52. — Steam  shovel  cost  distribution  chart. 


•§ 


0.50, 


3   4   5    <b   1    8    9  10  20  16   16  14-  12  10  6    64-20 
Thousand  Cubic  Yards  of  Material  Handed  per  Shift(AI I  Shovels) 


FIG.  53. — Steam  shovel  overhead  cost  chart. 


230  STEAM  SHOVEL  MINING 

age  of  1000  cu.  yd.  per  shovel  shift.  Reference  to  Fig.  53  shows 
that  with  all  shovels  working  double  shift  (viz.,  six)  loading  an 
average  of  12,000  cu.  yd.  per  shift,  the  overhead  expense  of 
production  at  this  rate  is  $0.072  per  cu.  yd.  This  cost  chart  is 
based  upon  the  total  overhead  cost  for  six  shovels  per  single-shift 
month  of  $14,217.98,  or  $25,645.66  per  double-shift  month,  or  of 
$473.93  per  single-shift  and  $854.85  per  double-shift  day.  The 
items  aggregating  these  totals  are  as  follows.  The  component 
factors  are  expressed  in  percentage  of  single  and  double  shifts. 

STEAM-SHOVEL  OVERHEAD  COSTS 

Single-shift  Double-shift 
Per  cent.         Per  cent. 

Water  and  water  lines 2 . 63  8 . 20 

Building  repairs 3 . 50  7 . 34 

General  expense 63 . 00  59 . 80 

Stable  expense 2 . 74  2 . 20 

Machine  shop 9 . 60  7.17 

Electric  power 4 . 43  2.18 

Engineering  and  surveying 4 . 22  3 . 40 

Sampling  and  assaying 1 . 62  3 . 77 

Steam-crane  expense 2 . 64  2  34 

Carpenter  shop 0 . 40  0 . 26 

Property  taxes 5.22  3.34 


100.00        100.00 

The  operating  cost  is  found  from  the  chart,  Fig.  55.  At  the 
average  rate  of  production  of  1000  cu.  yd.  per  day  the  cost  per 
cu.  yd.  is  $0.051.  The  cost  curve  is  based  on  the  average  cost 
per  steam-shovel  shift  for  the  entire  year  1914,  during  which  a 
total  of  4617  shifts  were  worked  at  the  following  cost. 

STEAM-SHOVEL  OPERATING  COSTS 

Total  cost        Cost  per  shift 

Shovel  labor $64,868.57  $14.05 

Fuel 65,941.92  14.28 

Supplies  and  repairs 55,258.73  11.96 

Pit  labor 51,523.68  11.16 


$237,592.90       $51.45 

The  locomotive  service  cost  per  steam-shovel  shift  is  found 
from  the  chart  of  Fig.  54.  Assuming  that  an  average  of  two  lo- 
comotives attend  each  shovel  the  cost  of  this  service  is  $0.084 
per  cu.  yd.  of  material.  The  chart  is  based  upon  average  costs, 


COST  OF  SHOVEL  WORK 


231 


which  include  all  accounts  chargeable  to  transportation,  for  the 
entire  year  1914,  as  follows: 

LOCOMOTIVE  COST  PER  SHOVEI^SHIFT 

Cost  per  9-hr,  shift 

Locomotive  labor $11 . 28 

Fuel 14.30 

Supplies  and  repairs 3 . 83 

Yard  crew  expense .  .  .  .• 0 . 88 

Track  maintenance 1 1 . 42 


Total  cost  of  one  locomotive $41 . 71 

Cost  of  two  locomotives $83 . 42 

The   cost   per   cubic   yard   then   becomes:  overhead,    $0.072; 
operating;  $0.051;  locomotive  service,  $0.084;  total,  $0.207. 


$026 
0.25 

~S  Q24 

==5  0-23 

a  0.22 

5  O.W 


tu, 


0.12 


£.   O.W 

8  o.oe 
giooe 

'•£   Q07 


0.05 


ill 


Cubic  Yards  of  Material  Handled  per  Steam 
Shovel  Shrft- 

FIG.  54. — Locomotive  operating 
cost  chart. 


Cubic  Yards  of  Material  Handled  per  Sfeam 
Shovel  Shiff 

FIG.  55. — Steam  shovel  operating 
cost  chart. 


This  cost  is  not  the  complete  cost,  however,  as  such  items  as 
drilling  and  blasting  and  dump  labor  must  be  handled  separately 
for  ore  and  waste.  The  charts  should  be  replotted  as  often  as 


232  STEAM  SHOVEL  MINING 

governing  cost  changes  warrant,  otherwise  they  would  give 
erroneous  results.  From  these  results  a  summary  chart  may 
be  plotted  and  kept  handy  for  ready  inspection,  which  will 
show  from  day  to  day  and  cumulatively  how  the  cost  and  efficiency 
of  the  work  is  going. 

It  will  be  noted  that  variations  in  the  numbers  of  shovels  operat- 
ing, due  to  repairs  or  other  causes,  will  affect  the  results  from 
these  curves.  Furthermore  the  best  balance  of  equipment  may 
be  determined  in  this  way,  since  it  will  be  seen  that  in  case  the 
train  service  to  any  shovel  is  poor,  the  yardage  of  that  shovel 
will  be  materially  reduced,  running  up  the  cost  per  cubic  yard 
for  that  particular  shovel;  and  again,  if  too  much  train  service 
is  assigned  to  a  shovel  it  may  be  quite  possible  to  increase  the 
yardage  from  that  particular  shovel,  but  only  at  a  high  total 
train  service  expense,  so  that  the  cost  per  cubic  yaid  will  again 
be  higher  than  where  a  better  balance  is  maintained.  With 
graphic  charts  of  this  kind  it  is  not  difficult  to  educate  foremen 
to  a  keen  appreciation  of  the  economics  of  the  problem,  and  they 
are  quick  to  put  this  into  practice. 

For  the  use  of  operating  officials  and  for  means  of  comparison 
a  consolidated  daily  graphic  chart  may  be  kept  showing  the  fol- 
lowing data. 

1.  The  total  operating  cost  per  cubic  yard  of  stripping  and  per  ton  of 
ore.     The  total  ordinates  of  such  a  curve  will  be  built  up  of: 

(a)  Supervision  and  engineering — Color  "A" 

(6)  Drilling  and  blasting  (based  on  average  cost) — Color  "B" 

(c)  Steam  shovel  operations — Color  "C" 

(d)  Pit  haulage —Color  "D" 

(e)  General  expense — Color  "  E  " 

(/)    Renewals —Color  " F" 

(g)  Water  supply  and  miscellaneous — Color  "G" 

(h)  Taxes  (to  be  added  in  case  of  ore  bearing 

same) : — Color  "  H  " 

2.  Cubic  yards  per  steam  shovel  shift  (day  and  night). 

3.  Cubic  yards  per  locomotive  shift. 

4.  Delays  in  percentage  of  total  time  in  service.  • 

The  delays  may  likewise  be  plotted  with  cumulative  ordinates  in  colors 
representing  delays  due  to: 

(a)  Blasting ' —Color  "a" 

(6)  Water,  moving,  repairs  and  miscellaneous.  .  . — Color  "b" 

(c)  Waiting  for  ore  cars — Color  "  c  " 

(d)  Waiting  for  waste  cars .  . — Color  "d" 


COST  OF  SHOVEL  WORK  233 

5.  Added  to  4  may  be  a  line  indicating  percentage  of  overtime  worked 

6.  Ratio  of  locomotive  shifts  to  steam-shovel  shifts. 

7.  Average  number  of  cars  in  service  per  locomotive. 

8.  Total  cubic  yards  overburden  removed. 

9.  Total  tons  ore  removed. 

10.  Average  grade  of  ore  removed. 

At  the  end  of  the  month  and  end  of  the  year,  the  averages 
of  these  results  may  be  struck  for  comparison. 

Office  Tabulations. — For  the  purpose  of  office  records  monthly 
tabulations  of  results  may  be  made  up  which  will  show  both  the 
total  costs  and  the  costs  per  cu.  yd.  and  per  ton.  Such  state- 
ments will  be  found  very  useful. 

TABULATION  I 

This  will  show  the  results  by  months  and  by  years  of  the  following  items: 
Yardage — total  cubic  yards  overburden  (or  tons  of  ore  shipped). 
Steam  shovels — total  shifts  and  average  number  in  service. 
Steam  shovel  operation. 

Total  shovel  labor  and  cost  per  cubic  yard  or  ton. 

Total  fuel  and  cost  per  cubic  yard  or  ton. 

Total  supplies,  repairs  and  cost  per  cubic  yard  or  ton. 

Total  pit  labor  and  cost  per  cubic  yard  or  ton. 
Locomotive  and  train  crew  service. 

Total  locomotive  labor  and  cost  per  cubic  yard  or  ton. 

Total  locomotive  fuel  and  cost  per  cubic  yard  or  ton. 

Total  supplies  and  repairs  and  cost  per  cubic  yard  or  ton. 

Total  yard  and  train  crews  and  cost  per  cubic  yard  or  ton. 

Total  dump  labor  and  cost  per  cubic  yard  or  ton. 

Total  track  maintenance  and  cost  per  cubic  yard  or  ton. 

Total  car  repairs  and  cost  per  cubic  yard  or  ton. 
Supervision. 

Total  superintendents  and  foremen  and  cost  per  cubic  yard  or  ton. 

Engineering  and  surveying  and  cost  per  cubic  yard  or  ton. 
Drilling  and  blasting. 

Total  drill  expense  and  cost  per  cubic  yard  or  ton. 

Total  labor  and  cost  per  cubic  yard  or  ton. 

Total  explosives  and  cost  per  cubic  yard  or  ton. 
Water  supply — total  cost  and  cost  per  cu.  yd.  or  ton. 
Miscellaneous  maintenance,  buildings,  repairs,   etc. — total  cost  and    cost 

per  cu.  yd.  or  ton. 

Renewals,  reserve  fund — total  cost  and  cost  per  cu.  yd.  or  ton  . 
General  expense — total  cost  and  cost  per  cu.  yd.  or  ton. 
Total  orebody  stripping  cost  deferred  and  cost  per  cu.  yd.  or  ton. 
Total  track  or  other  costs  deferred. 
Total  cost  deferred. 
Less  deferred  costs  charged  to  mining. 
Ledger  balance  deferred  charges  account. 


234  STEAM  SHOVEL  MINING 

To  the  ore  account  may  be  added: 

Total  taxes  and  cost  per  ton  (dry  weight). 
Total  pit  pumping  and  cost  per  ton. 
Total  operating  cost  and  cost  per  ton. 
Total  ore  cost  and  cost  per  ton. 
Totals  and  averages  to  date. 

A  .different  arrangement  and  division  of  the  detailed  cost  of 
operations  may  be  carried  from  the  accounts  to  tabulations  pre- 
pared to  show  the  details  of  Labor,  Supplies  and  General  and 
miscellaneous  expenses  distributed  to  the  various  operations  in 
the  following  way: 

The  headings  for  the  different  columns  will  designate  the 
different  operations:  Steam  shovels,  Locomotives,  Track  repairs, 
Blasting,  Well  drills,  Water  lines,  Car  repairs,  Dumps,  Pumping, 
General  expense,  Miscellaneous,  and  the  last  two  columns  will 
be  Total  cost  and  Average  cost  per  cu.  yd.  (or  per  ton).  Each 
of  these  columns  will  carry  on  their  right  a  column  called  Acct. 
No.  — ,  which  will  give  the  number  of  the  account  from  which 
the  amount  is  taken. 

Running  down  the  chart  in  the  margin  will  be,  first,  the  Labor 
items:  Supt.  and  foremen,  Shovel  engineers,  Shovel  cranemen, 
Shovel  firemen,  Pitmen,  Locomotive  engineers,  Locomotive 
firemen,  Locomotive  brakemen,  Yardmasters  and  switchtenders, 
Trackmen,  Drillers  and  blasters,  Dumpmen,  Blacksmiths  and 
helpers,  Carpenters  and  helpers,  Machinists  and  helpers.  Lab- 
orers, Teamsters.  A  horizontal  line  will  here  be  drawn  and  the 
total  Labor  cost  and  cost  per  cu.  yd.  (or  ton)  will  be  footed 
up  for  each  of  the  columns.  Following  under  this  in  the  marginal 
column  items  of  Supplies  will  come:  Pipe  &  fittings,  Iron  & 
steel,  Explosives,  Steam  shovel  and  locomotive  parts,  Oil, 
waste,  etc.,  Tools,  Railroad  and  drill  supplies,  Fuel,  Dump 
car  parts,  General  mine  supplies.  A  second  horizontal  line  drawn 
here  will  foot  up  the  total  cost  of  Supplies  and  show  the  cost 
per  cu.  yd.  (or  per  ton)  for  each  of  the  columns.  Following 
under  this  in  the  marginal  column  will  come  the  General  and 
Miscellaneous  items:  Stable  expense,  Shop  expense,  Steam  crane, 
Electric  power,  Building  repairs,  Water  lines,  Engineering  and 
surveying,  Taxes,  Steam  shovel  and  locomotive  renewals, 
General  expense,  Sampling  and  Assaying  and  Miscellaneous. 
A  third  horizontal  line  will  be  drawn  here  and  the  General  and 
Miscellaneous  total  amounts  and  amounts  per  cu.  yd,  (or  ton) 


COST  OF  SHOVEL  WORK 


235 


will  be  footed  up.  A  fourth  and  final  horizontal  line  will  then 
be  drawn  and  the  grand  total  amounts  and  amounts  per  cu.  yd. 
(or  ton)  will  be  footed  up  for  all  items. 

A  recapitulation  of  the  above  may  be  added  at  the  bottom  in 
this  form. 


Costs  this  month 

Total 
Amount 

Per  cu.  yd. 

(or  dry  ton) 

Pay  roll  

Supplies                                 

General  expense 

Miscellaneous  
Total  cost 

Numbergof 

Quantities  this  month 

Cu    yd    overburden 

(Dry  tons  ore)  

Shovels  employed  (individual  shovel  numbers)  .  . 
Cu    yd    per  shovel 

(Dry  tons  per  shovel)       

Monthly  Statistics. — A  monthly  statistical  chart,  giving  the 
information  indicated  in  Table  19  below  will  be  found  very  use- 
ful and  interesting.  These  items  may  be  rearranged  or  added 
to  in  any  way  desired  by  the  local  management.  Careful 
intelligent  study  and  analysis  of  costs  will  invariably  repay  all 
effort  and  expense  so  spent  and  is  one  of  the  best  methods  of 
picking  out  weak  spots,  reducing  the  costs  and  increasing  the 
efficiency  of  the  work.  The  accounting  and  engineering  de- 
partments should  work  in  close  harmony  with  the  management 
in  studies  of  this  kind. 

All  of  the  foregoing  data  will  form  the  basis  on  which  periodical 
reports  will  be  submitted  by  the  mine  management  to  the  general 
management,  and  then  in  more  condensed  form  to  the  property 
owners. 


236 


STEAM  SHOVEL  MINING 


TABLE  19. — MINING  DEPARTMENT,  STEAM  SHOVEL  MINING  DATA 
AND  STATISTICS 


12  months, 
last  year 


This  year 


Jan.        Feb.      March     ApHl 


YARDAGE 


Ore — dry  tons  shipped 

Ore — cu.  yd.  (1'cu.  yd.  in  place  = 

2.16  dry  tons) 

Overburden  to  dumps  (cu.  yd.  in 

place) 

Total  yardage  moved  (cu.  yd.  in 

place) 


STEAM  SHOVELS 


Steam  shovel  shifts,  9  hr.  in  ore  .  .  . 
Steam  shovel  shifts,  9  hr.  in  waste .  . 
Average  yardage  per  shovel  shift 

operating  in  ore 

Average  yardage  per  shovel  shift 

operating  in  waste 

Tons  of  coal  used  by  steam  shovels . 
Cost  of  shovel  coal  per  ton  (F.  O.  B.) 
Tons  of  coal  used  per  shovel  shift. .  . 
Lb.  of  coal  per  ton  of  ore  shipped.  . 
Lb.  of  coal  per  cu.  yd.  of  waste 

moved 

LOCOMOTIVE 

Total  shifts  of  9  hr.  in  ore 

Total  shifts  of  9  hr.  in  waste 

Tons  of  coal  used  on  locomotives . . . 
Tons  of  coal  per  locomotive  shift. . . 
Cost  of  locomotive  coal  per  ton 

(F.O.B. ) 

Lb.  of  coal  per  ton  of  ore  shipped.  . 
Lb.  of  coal  per  cu.  yd.  of  waste 

moved 

Cost  per  ton-mile  of  material  handled 

WELL  DRILLS 

Drill  shifts  of  9  hr.  worked 

Number  of  blast  holes  drilled  in  ore .  j 
Number  of  blast  holes  drilled  in  waste 

Number  of  feet  drilled  in  ore 

Number  of  feet  drilled  in  waste. . 


COST  OF  SHOVEL  WORK 


237 


WELL  DRILLS  (cont.) 


12  months, 
last  year 


This  year 


Jan.       Feb.      March     April 


Lb.  of  coal  per  foot  drilled 

Lb.  of  coal  per  ton  of  ore  shipped.  . 

Average  footage  per  9  hr.  shift 

Total  number  6  in.  holes  drilled 

Total  number  6  in.  holes  shot 

Tons  of  ore  broken  per  foot  of  hole 

drilled 

Cu.   yd.   waste  broken  per  foot  hole 

drilled 

EXPLOSIVES 

Lb.    of    principal    H.    E.    per    1000 

cu.  yd.  waste 

Lb.  of  each  other  type  used  per  1000 

cu.  yd.  of  waste 

Lb.  of  principal  H.  E.  per  1000  tons 

of  ore  shipped 

Lb.  of  each  other  type  used  per  1000 

tons  of  ore  shipped 

Cost    exploders    per    1000    cu.    yd. 

waste  or  ore 

LUBRICATION 

Gal.    lubricating    oil    per    .ton    ore 

shipped 

Lb.  grease  per  ton  ore  shipped 

Cost  of  lubricating  oil  and  grease  per 

ton  ore  shipped 

Gal.  lubricating  oil  per  cu.  yd. 

waste 

Lb.  grease  per  cu.  yd.  waste 

Cost  lubricating  oil  and  grease  per 

cu.  yd.  waste 

Record  month  for  material  moved 
Best  record  for  one  shovel  in  one  month 

Tons  of  material  handled  per  man 
per  shift 


This  year 


Jan     |    Feb       March      April 


238  STEAM  SHOVEL  MINING 

The  mine  accounts  will  be  carried  on  cost  sheets,  the  following  outline 
of  which  may  serve  as  a  fair  example. 

1.  Pit  stripping  deferred. 

2.  Equipment  and  miscellaneous  construction  deferred. 

3.  Pit  mine  cost  sheet. 

4.  General  expense. 

5.  Shovel  and  locomotive  renewals. 

6.  Taxes. 

7.  Profit  and  loss. 

8.  Accounts  receivable. 

9.  Inventory  of  supplies — material  in  transit  and  reconciliation  of  sup- 

ply ledger. 

10.  Boarding  house. 

11.  Machine  shop. 

12.  Electric  shop. 

13.  Stable  or  truck  operations. 

14.  Churn  drill  prospecting  and  developing. 
15. \  Steam  crane  expense. 

16.  f*ay  roll  distribution. 

S$egreg3fion'of  costs  as  desired. 
nual  Reports. — The  annual  reports  of  mining  companies 
idely  variable  but  some  of  the  best  of  them  prepare  account- 
ant's  repor.±s   which   show   the  following  information,  and  the 
records*kept  should  be  such  that  this  may  readily  be  obtained. 

•» 

•  >         v    . 

Exhibit  "A" 

temen^  of  Assets  "and  Liabilities. 

.    Exhibit  "B" 

Statement  of  Operations. 

This  will  briefly  show  operating  revenue,  operating  expenses, 
miscellaneous  income  and  receipts,  other  charges,  and  a  surplus 
or  defteit  from  such  operations. 

Exhibit  "C" 

Current  assets  and  current  liabilities  and  investments. 

The  investments  will  be  detailed  at  face  and  book  values. 

Under  Exhibit  "A"  may  be  prepared  a  schedule  showing 
composition  of  increase  or  decrease  in  surplus  funds.  Also  a 
schedule  showing  ''Prepaid  ore  expense"  due  to  stripping  of 
overburden  ahead  of  ore  removal. 


COST  OF  SHOVEL  WORK  239 

Any  additions  to  property  or  plant  should  be  set  forth. 

A  careful  study  of  the  annual  reports  of  the  companies  whose 
costs  have  been  herein  illustrated  will  serve  as  an  excellent  guide 
as  to  the  material  required  for  an  intelligent  clear  report  to 
property  owners. 


CHAPTER  VIII 
ADMINISTRATION 

Introductory. — The  administration  of  open  pit  mines  is  of 
course  based  on  the  same  general  lines  as  is  that  of  any  other 
mining  enterprise,  but  it  is  more  usual  to  find  the  life  of  open 
pit  mines  longer  and  better  defined  than  in  the  case  of  most 
underground  mines.  In  other  words  they  are  usually  more 
fully  developed  than  underground  mines.  This  makes  it  pos- 
sible to  treat  them  more  as  great  industrial  enterprises,  and  as 
such  more  care  and  money  can  be  expended  on  the  plans  for 
their  operation. 

There  are  a  number  of  general  problems  which  should  be 
determined  as  early  as  convenient,  which  will  have  a  bearing 
on  the  administrative  policy  of  the  property.  Among  these  may 
be  mentioned  the  ratio  of  output  desired  to  be  maintained  with 
a  known  developed  and  probable  tonnage,  and  as  a  corillary 
to  this  how  much  capital  may  justifiably  be  spent  in  equipment 
to  realize  such  a  ratio  of  output;  the  lowest  grade  of  ore  that  can 
be  considered  profitable  to  treat  when  by  treating  it  the  treat- 
ment of  higher  grade  ore  is  postponed;  the  amount  of  prepaid 
stripping  that  may  justifiably  be  carried  to  insure  steady  working 
conditions  and  an  average  grade  of  ore.  The  labor  problem  will 
also  require  the  constant  care  of  the  management. 

Ratio  of  Output. — Theoretically,  the  value  of  a  property  is 
directly  proportional  to  the  speed  with  which  its  latent  value 
may  be  converted  into  actual  money.  The  present  value  of  a 
dollar  payable  in  one  year  is  double  that  of  a  dollar  payable  in 
twelve  years,  and  four  times  that  of  a  dollar  payable  in  twenty- 
four  years  (interest  at  6  per  cent.).  Likewise,  a  value  which 
cannot  be  liquidated  in  less  than  forty  years  is  not  worth  ten 
cents  on  the  dollar  today.  Furthermore  extensive  large  scale 
operations  usually  result  in  low  production  costs  because  of  a 
large  divisor  for  all  fixed  and  general  charges  not  proportional 
to  production. 

On  the  other  hand  there  are  practical  and  physical  limitations 
to  maximum  production  which  usually  necessitate  some  sort  of  a 

240 


ADMINISTRA  TION  241 

balance  or  compromise  with  the  theoretical  view.  The  greater 
the  planned  production,  the  greater  will  be  the  amount  of  in- 
vested capital  required.  This  will  be  tied  up  in  all  sorts  of 
equipment,  in  the  necessary  extensive  development,  and  in 
many  cases  in  a  large  amount  of  prepaid  stripping.  It  must  be 
remembered  that  this  bears  interest  also,  so  that  a  dollar  invested 
today  at  6  per  cent,  will  be  worth  two  dollars  in  twelve  years  and 
so  on. 

Next  the  physical  characteristics  of  the  mine  may  easily  be 
such  that  too  intensive  a  production  would  only  tend  to  inef- 
ficiency due  to  cramping  or  crowding  of  working  conditions  in 
the  available  territory.  This  might  entail  losses  of  valuable 
ore  which  could  not  be  taken  out  in  keeping  pace  with  the  general 
program. 

Third,  there  is  the  question  of  supply  and  demand  of  the 
commodity  produced.  The  price  of  most  commodities  is  subject 
to  considerable  fluctuation  and  many  properties  find  it  necessary 
to  somewhat  govern  their  production  in  an  effort  to  maintain  a 
fair  price  for  the  product.  With  an  excess  of  production  over 
demand,  prices  usually  " soften"  so  that  it  may  easily  take  three 
tons  of  ore  to  show  the  same  profit  as  would  be  had  from  two 
tons  if  the  demand  was  just  met  by  the  supply.  At  the  present 
time  taxation  is  such  that  excess  profits,  which  might  in  certain 
^ases  be  made  by  maximum  production,  would  be  considerably 
reduced.  In  so  far  as  market  prices  are  concerned,  a  property 
might  be  operated  at  a  high  rate  of  production  with  a  view  to 
storing  the  commodity  during  low  prices  and  selling  heavily 
at  high  prices,  but  there  will  then  be  interest  charges  to  consider 
on  the  cost  of  production  as  well  as  the  actual  money  so  tied  up 
and  this  will  tend  to  cause  wide  fluctuations  in  the  dividend 
paying  power  of  the  property.  Stock  in  most  metal  producing 
companies  is  rather  widely  held  and  subject  to  such  various 
policies  of  administration  that  concerted  action  cannot  be 
expected  even  if  anti-trust  laws  were  not  in  effect  to  prevent 
collective  action. 

In  the  final  analysis  therefore  a  production  figure  will  usually  be 
decided  upon  which  will  be  high  enough  to  secure  good  operating 
cost  and  permit  of  first-class  equipment,  insuring  a  good  rate  of 
interest  on  the  total  estimated  and  available  capital  investment. 
In  planning  such  an  average  output  it  will,  of  course,  be  wise  to  so 
arrange  the  operations  and  plant  that  they  have  some  economic 

16 


242 


STEAM  SHOVEL  MINING 


flexibility,  and,  if  later  conditions  warrant,  that  the  plant  and 
output  can  be  extended  economically. 

Example. — The  solution  of  a  problem  of  this  kind  presents  some 
interesting  features  and  a  hypothetical  example  will  be  given  to 
illustrate  the  method  used  by  the  writer.  In  this  problem 
it  is  assumed  that  we  have  a  property  producing  about  9000  tons 
per  day  and  having  a  developed  tonnage  of  about  60,000,000  tons, 


I 

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VE  A,  Shows  'Present  Value  "o 
•jut,  Also  Life  for  such  Output. 

VE  B,  Shows  New  Cap!  tallnpt. 
y  Tonnage  Output.  Notet^yiQ, 
10  Tons  Dailu  and  &7SO,  000  for 
tional. 
VE  C,  Shows  the  Ratio  oflm 
Greater  Output  to  New  Capita 
Capita/  Input  Reauf  red  to  ob- 

ft                                        -r 

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it  Required  to  Increa* 
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each  1000  TonsperDat 

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"0     Z     4     fe     8     10    12    14    16     18   20    22  24    26    28   30   32    34  36    38  40 

Life  of  Property  in  Years 
FIG.  56. — Valuation  chart;  ratio  of  output. 

which  would  give  it  an  assured  life  of  about  18  years  and  a  present 
value  of  about  $34,000,000. l  It  is  further  assumed  that  with  an 
expenditure  of  only  $340,000  the  plant  could  be  increased  to  an 
output  of  10,000  tons  per  day,  and  that  for  each  additional  expen- 
diture of  $750,000  it  could  be  increased  in  increments  of  1000 

1  It  is  assumed  that  the  method  of  arriving  at  the  "present  value"  of  a 
property  is  understood, 


ADMINISTRA  TION  243 

tons  per  day.  It  is  desired  to  determine  whether  or  not  it  is 
justifiable  to  increase  the  production  and  if  so  to  about  what 
extent.  The  curves  on  chart,  Fig.,  56  have  been  drawn  to 
show  the  solution  graphically.  Curve  A  of  this  chart  is  so  plotted 
that  by  noting  any  ordinate  on  the  right  margin  and  then  running 
over  to  the  left  to  the  intersection  of  this  curve,  and  from  this 
point  dropping  down  to  the  bottom  abscissa,  the  life  of  the  prop- 
erty in  years  will  be  found;  or,  by  simply  continuing  across  to 
the  left  hand  margin,  the  "present  value"  of  the  property 
will  be  found.  For  example,  with  a  daily  output  of  12,000  tons, 
the  life  will  be  about  13  years,  and  the  present  value  will  be  about 
$38,000,000. 

A  set  of  co-ordinates  was  drawn  from  a  point  on  the  curve  cor- 
responding to  the  present  output  of  the  property  of  9000  tons 
per  day.  The  auxiliary  ordinate  is  plotted  to  represent  the  new 
capital  required  to  increase  the  daily  output  and  the  auxiliary 
abscissa  to  represent  the  life  of  the  mine  with  various  daily  out- 
puts. On  this  basis  curve  B  was  plotted.  The  difference  in  the 
ordinates  (on  the  left  hand  margin)  between  curves  A  and  B, 
shows  the  net  increase  in  the  present  value  which  can  be  made  by 
additional  plant  capacity  up  to  30,000  tons  per  day.  At  30,000 
tons  per  day,  curve  B  crosses  curve  A  and  would  there  show  no 
gain  in  present  value  and  a  higher  output  would  show  a  loss. 
Curve  B  shows  that  the  maximum  net  increase  in  present  value 
is  reached  when  the  output  is  increased  to  16,000  tons  per  day. 
This  net  increase  is  about  $4,000,000,  for  an  expenditure  of 
$5,000,000,  or  the  gross  increase  in  present  value  is  $9,000,000. 
Curve  C  has  been  plotted  merely  to  show  the  maximum  increased 
present  value  accruing  with  new  capital  input  increments.  In 
other  words,  curve  C  simply  shows  the  ratio  of  the  net  increase 
in  present  value  to  the  necessary  new  capital  expended  in  increas- 
ing the  output  to  increase  the  present  value.  For  example,  by 
increasing  the  output  by  10  per  cent,  with  the  expenditure  of 
$340,000  the  present  value  is  increased  by  $1,400,000  or  the 
ratio  is  over  4  to  1.  Beyond  'this  output,  the  expenditures  are 
assumed  to  be  heavier  per  1000  tons  increase  capacity,  so  that  the 
curve  flattens  out.  It  is  shown,  however,  that  by  increasing  the 
tonnage  output  to  14,000  tons  per  day,  this  ratio  is  still  as  high 
as  2  to  1,  and  for  12,000  tons  per  day  it  is  2.3  to  1;  in  other  words 
for  every  new  dollar  spent  in  increasing  the  plant  capacity  to 
12,000  tons  over  9000  tons,  the  present  value  of  the  property 


244  STEAM  SHOVEL  MINING 

is  increased  $2.30.  These  curves  automatically  take  care  of 
the  interest  charges  on  the  new  capital  invested,  except  for  the 
period  between  beginning  the  expenditure  and  the  time  at  which 
benefit  from  the  increased  production  can  be  realized.  This 
would  be  a  relatively  insignificant  amount. 

In  the  same  way  a  set  of  curves  may  be  plotted  covering  any 
problem  when  the  necessary  data  are  as  accurately  known.  In 
this  example,  unless  some  practical  reason  due  to  operating 
conditions  forbids,  it  would  be  advisable  to  increase  the  output  of 
this  property  up  to,  say,  16,000  tons  per  day,  at  which  figure  the 
maximum  net  increase  in  present  value  is  shown  to  be  attained. 

Lowest  Grade  of  Ore  that  Should  be  Worked. — It  is  necessary 
to  determine  the  lowest  grade  of  ore  that  can  be  mined  at  a  profit 
under  given  costs  of  mining  and  overburden  ratio;  or  stated 
another  way  it  is  necessary  to  know  how  much  can  be  expended  on 
mining  and  stripping  ore  of  a  given  tenor.  In  all  pits  there  are 
variations  in  the  ore-overburden  ratio  and  in  the  tenor  of  the  ore; 
there  are  also  variations  in  the  selling  price  of  the  product  which 
may  materially  effect  the  economics  of  the  question,  but  to  plan 
work  ahead,  price  of  commodity  and  cost  of  working  must  to  a 
certain  extent  be  assumed.  In  Chap.  VI  this  subject  was 
discussed  and  curves  were  given  to  illustrate.  It  is  not  only 
necessary  to  avoid  shipping  material  on  which  an  operating  loss 
is  borne,  but  it  is  also  necessary  to  avoid  shipping  material  which 
will  not  show  an  average  profit  sufficient  to  pay  fair  dividend 
requirements.  In  fact  fair  dividend  requirements  may  be 
considered  in  truth  a  part  of  the  operating  expense.  A  copper 
mine  might  meet  all  operating  expenses  nicely  on  an  ore  carrying 
1  per  cent,  copper,  but  to  pay  dividends  to  its  stockholders  it 
might  require  an  ore  averaging  1.5  per  cent,  copper. 

It  may  be  that  in  mining  and  stripping,  much  "  border  "  ore  will 
be  loaded  by  the  shovels  and  it  becomes  a  question  whether  to 
put  it  on  the  dump  or  send  it  to  the  mill.  The  expense  of  mining 
it  has  already  been  met,  to  put  it  on  the  dump  will  entail  some 
additional  expense  and  it  will  therefore  only  have  to  stand  trans- 
transportation  and  treatment  costs  over  and  above  the  cost  of 
wasting  it.  The  mine  may  have  plenty  of  capacity  to  load  all  mill 
requirements  and  the  mine  management  may  not  be  especially 
interested  in  what  becomes  of  the  product  after  it  has  been 
moved,  but  it  must  be  remembered  that  the  rest  of  the  plant  has  a 
limited  capacity  and  that  for  every  ton  of  poor  material  put 


ADMINISTRATION  245 

through,  a  ton  of  average  material  has  been  displaced.  All  of 
these  factors  must  be  considered  if  the  earnings  are  to  be  kept  up. 
The  ideal  arrangement  would  be  to  keep  the  mill  full  of  high 
grade  material  as  long  as  it  lasted  and  as  this  became  exhausted 
lower  grade  material  could  then  be  treated.  In  this  way,  other 
things  remaining  constant,  the  maximum  money  would  be  pro- 
duced in  the  shortest  time,  and  this  would  be  available  to  draw 
interest.  Such  an  arrangement  cannot  be  broadly  met  due  to  the 
very  nature  of  the  mining  operations  and  to  the  necessity  of 
conserving  ores  which  are  to  a  fair  degree  profitable.  Even  with 
mines  having  a  great  length  of  life,  the  justice  in  a  reasonable 
policy  of  conservation  comes  into  consideration  along  with  the 
academic  economics.  It  sometimes  'happens,  however,  that  low 
grade  material  can  be  segregated  in  dumps  apart  from  the 
straight  waste,  and  these  may  be  reserved  for  later  treatment. 
If  so,  the  plant  maybe  enabled  to  produce  more  wealth  in  a  short 
time,  making  the  property  of  greater  "  present  value,"  and  the  low 
grade  material  may  also  be  saved  and  some  day  may  add  con- 
siderable value  to  the  property.  In  this  question,  as  in  most 
others,  it  is  a  question  of  compromise,  but  the  compromise  should 
be  based  on  a  full  understanding  of  the  consequences.  The  gra- 
phic solution  of  the  problem  as  explained  in  Chap.  VI  has  been 
found  very  helpful  in  educating  mine  operatives  to  an  apprecia- 
tion of  the  consequences  and  when  they  are  understood  there  is 
much  less  tendency  to  ship  material  known  to  be  poor. 

Amount  of  Prepaid  Strippings. — This  problem  is  somewhat 
comparable  to  the  extent  of  development  in  vein  mines,  not  so 
much  in  the  light  of  adding  to  ore  reserves,  which  may  better  be 
called  prospecting,  as  to  the  opening  up  of  tonnage  ready  for 
extraction.  It  has  been  the  policy  at  some  of  the  Mesabi  iron 
mines  to  completely  strip  the  ore  body  before  extracting  the  ore. 
Such  work  has  often  been  done  by  contractors  or  equipment  not 
needed  elsewhere  has  been  put  to  work  on  such  jobs.  Under 
certain  conditions  this  policy  may  be  entirely  justifiable  and  it  is 
certainly  advantageous  in  planning  the  ore  mining,  but  it  does  tie 
up  considerable  money,  often  in  excess  of  that  actually  required 
to  carry  on  with  the  required  ore  extraction.  Furthermore, 
stripping  banks  left  exposed  to  the  weather  for  a  number  of  years 
have  a  tendency  to  slough  off  into  the  pit  and  may  require  more 
or  less  cleaning  up  and  repair.  Stripping  should,  however,  be 
carried  far  enough  ahead  to  insure  safe,  clean  and  unhampered 


246  STEAM  SHOVEL  MINING 

mining  of  average  grade  ore.  The  waste  should  be  moved  far 
enough  back  to  permit  the  ore  benches  being  carried  in  the  best 
practical  manner  for  blasting  and  loading.  Furthermore,  with 
the  stripping  carried  well  ahead  of  mining  operations  so  that  it 
could  be  discontinued  for  say  six  months  without  inconvenience, 
it  will  be  found  of  much  advantage  in'  the  event  of  labor  troubles, 
or  an  unexpected  shortage  of  labor  or  supplies,  or  accidents  to 
shipping  equipment.  To  justify  carrying  it  beyond  such  require- 
ments or  contingencies,  there  must  be.  some  good  local  reasons; 
otherwise,  the  interest  charge  on  the  sum  so  spent  will  not  be 
warranted.  In  some  localities,  due  to  climatic  or  other  local 
conditions,  stripping  can  best  be  done  periodically  and  where 
these  conditions  are  met,  the  advance  stripping  may  at  times  be 
considerable.  It  is  usually  found  cheaper  to  crowd  stripping  in 
in  summer  and  work  it  but  lightly  in  winter.  Also  it  may  be 
found  that  labor  or  supplies  are  cheaper  at  certain  periods  than  at 
others  and  it  may  then  pay  to  push  the  work  when  these  con- 
ditions are  most  favorable.  It  may  also  prove  desirable  to  have 
several  pits  or  portions  of  a  deposit  opened  simultaneously,  in 
which  case  the  prepaid  stripping  will  probably  be  greater  than 
if  the  .entire  tonnage  was  taken  from  one  pit.  The  objections 
to  excess  stripping  are  simple  and  against  them  only  must  be 
weighed  local  conditions.  Care  and  study  should  be  given  that 
the  advance  stripping  is  removed  from  the  most  advantageous 
areas. 

Engineering  Work. — -The  careful  surveying  and  mapping  of 
the  property  should  be  kept  up.  All  of  the  month's  shovel  work, 
both  in  ore  and  waste,  is  cross-sectioned  every  month.  Stadia 
work  is  sufficiently  accurate  for  the  regular  monthly  reports,  but 
once  every  six  months  the  work  should  be  done  by  triangulation. 
The  cross-sections  are  taken  at  intervals  of  from  27  to  100  ft.,  the 
latter  is  the  practice  at  the  coppar  properties,  while  40  ft.  is  the 
distance  used  on  Mesabi  iron  mines.  The  27-ft.  interval  is 
convenient  for  direct  yardage  results.  These  results  are  plotted 
to  scale  on  cross-section  cloth,  and  the  areas  are  determined  by 
planimeter  or  triangles.  The  cross-sections  are  always  taken  at 
the  same  places  and  are  plotted  in  different  colors  so  that  each 
month's  work  is  easily  seen.  The  engineer's  estimates  are  checked 
by  the  railroad  weights  for  the  ore,  and  with  the  yardage  capacity 
of  the  waste  cars.  Much  of  the  cost  and  technical  data  are  based 
on  the  engineering  work.  Future  stripping  plans  will  usually 


ADMINISTRA  TION  247 

depend  in  large  measure  on  an  accurate  knowledge  of  the  orebody. 
For  this  purpose  sectional  models  are  very  useful.  Such  a  model 
may  be  made  up  of  1-in.  boards  set  vertically  on  a  scale  of  1 
in.  per  100  ft.  (horizontal  and  vertical).  On  one  face  of  each 
board  may  be  pasted  a  blue  print  cross-section  of  the  deposit 
at  that  point.  Such  cross-sections  will  have  been  made  up  of 
the  drill  hole  and  surface  data.  As  the  excavation  progresses 
these  boards  may  be  drawn  from  the  model  box  and  cut  out  to 
conform  to  the  pit  conditions.  Such  a  model  will  also  serve  to 
indicate  grade  of  ore  expectancies.  Bench  sampling  should  be 
carefully  and  frequently  done  and  the  results  of  the  assays 
quickly  reported.  When  a  shovel  is  working  in  " border"  ore 
the  samplers  should  be  most  vigilant.  This  work  will  invariably 
save  the  treatment  of  unpayable  material  and  often  the  wastage 
of  good  ore. 

Time  studies  of  certain  phases  of  the  work  will  often  be  useful 
in  securing  data  for  new  estimates. 

Labor. — Most  of  the  labor  employed  about  open-pit  mines  is 
unionized,  and,  with  the  exception  of  pit  and  dump  gangs,  is 
of  an  intelligent  type.  The  work  of  the  different  services  is 
closely  interdependent  so  that  inefficiency  in  one  is  almost  sure 
to  affect  the  others.  As  a  rule  the  shovel-workers'  unions  have 
displayed  a  spirit  of  fair  play.  The  train  crews  are  similar  to 
those  found  on  railroad  operation.  These  men  may  be  encouraged 
by  a  system  of  bonus  payments  such  as  used  on  the  Mesabi  range. 
At  times  this  is  effective  in  raising  efficiency.  Profit-sharing  in 
various  ways  is  now  being  tried  by  some  companies  but  that  is  a 
subject  in  itself.  Reports  may  be  prepared  each  month  showing 
the  average  yardage  handled  by  each  shovel  runner,  each  loco- 
motive crew;  the  footage  of  hole  drilled  by  each  driller;  and  the 
condition  in  which  each  operator  has  kept  his  machine.  These 
are  very  good  both  in  keeping  up  the  discipline  of  the  work 
through  inspection  and  in  being  able  to  rate  the  efficiency  of 
the  crews  through  the  records. 

It  is  highly  desirable  to  keep  the  labor  turnover  to  a  minimum. 
New  men  are  as  a  rule  of  decidedly  lower  efficiency  than  the  old 
crews,  familiar  and  educated  to  the  requirements  of  the  job.  New 
men  must  become  " acclimated,"  as  it  were,  to  all  of  the  local  con- 
ditions, and  many  even  to  the  ways  of  performing  their  tasks. 
For  this  education  the  company  must  pay. 

The  betterment  of  quarters,  food  and  places  of  amusement  or 


248          STEAM  SHOVEL  MINING 

recreation  for  workmen  has  a  very  marked  effect  in  securing  the 
best  men,  especially  if  they  have  families,  and  married  men  with 
families  are  usually  more  contented  and  steadier.  Wherever 
possible,  the  family  is  to  be  encouraged.  The  foremen  should  be 
kept  from  too  close  contact  with  their  crews  when  off  duty;  it 
makes  for  better  discipline. 

The  safety  of  the  workmen  is  a  subject  which  must  constantly 
be  looked  to.  There  is  always  present  a  certain  percentage  of 
men  who  are  careless  or  ignorant  of  their  dangers.  Safety  engi- 
neers are  employed  by  some  companies  to  make  careful  studies 
of  all  accidents,  of  exposed  machinery  parts,  shops,  handling  and 
care  of  explosives,  railroad  grade-crossings  and  many  other  simi- 
lar things.  These  men  should  work  in  close  co-operation  with  the 
medical  officers  as  well  as  with  the  managment.  The  elimination 
of  intoxicants  has  been  found  to  decrease  accidents  as  well  as  in- 
crease the.  general  efficiency,  prosperity  and  dependability  of  the 
men.  In  open-pit  work  it  is  especially  necessary  to  protect  men 
from  unnecessary  hardship  in  bad  weather.  Arrangement  for 
their  distribution  to  and  from  work  and  for  reasonable  shelter 
while  at  work  must  be  planned.  In  the  case  of  foreign  employees 
who  understand  but  little  English,  it  is  well  to  provide  them  with 
small  instruction  pamphlets  written  in  their  native  language. 
All  such  rules  as  have  to  do  with  the  handling  or  use  of  explosives, 
warning  signals  for  blasting,  trimming  banks,  repairing  equip- 
ment, use  of  intoxicants,  sanitary  rules,  hours  of  work,  time  of 
meals,  recreation  provision  and  similar  subjects  should  be  freely 
published  and  placed  in  all  hands  by  the  welfare  engineers. 
These  engineers  should  keep  careful  records  which  may  be  sub- 
mitted periodically  in  condensed  form  to  the  management.  It 
is  interesting  to  note  that  the  Minnesota  mine  inspector's  report 
for  1910,  referring  to  fatal  accidents  in  underground  and  open- 
pit  mining,  showed  3.32  per  1000  for  the  former  and  4.59  per  1000 
for  the  latter.  One  reason  given  was  that  open-pit  work  more 
nearly  resembles  railroading  than  mining,  and  hence  the  greater 
percentage  of  fatalities.  Whether  this  proportion  would  hold 
true  for  other  districts  is  not  known,  but  it  is  true  that  a  large 
proportion  of  open-pit  accidents  are  chargeable  to  the  train 
service;  misfires  and  premature  explosions  would  probably 
come  second.  The  time  has  arrived  when  workmen  are  seeking 
betterment  of  conditions,  and  aside  from  the  justice  or  ethics 
of  their  collective  stand,  it  is  highly  desirable  that  they  be  ac- 


ADMINISTRA  TION  249 

corded  as  just  treatment  as  is  humanly  possible.  The  great 
majority  are  not  unmindful  of  a  spirit  of  fair  dealing  and  their 
loyalty  and  contentment  is  generally  reflected  to  some  degree 
in  their  work. 


INDEX 


A-frame,  8 
Administration,  240-249 

amount  of  prepaid   strippings, 
245 

engineering  work,  246 

labor,  247 

lowest  grade  of  ore  profitable, 
244 

ratio  of  output,  240 
Aguew  iron  mine,  171 
Air  machine  drills,  139 
Ajax  Forge  Co.,  92 
Allis-Chalmers  breaker,  112 
Allis-Chalmers  Co.,  28 
Alpena  mine,  128 
American  Equipment  Co.,  27 
American  Locomotive  Co.,  27,  65 
American  Zinc  Lead  &  Smelting  Co., 

24 

Anderson,  J.  M.,  228 
Anthracite  coal  stripping,  129 

cost,  226 

Armstrong,  F.  H.,  36 
Atlantic  shovel,  27,  28,  45 

Baldwin  Locomotive  Works,  65 

Balkan  mine,  127 

Ball  Co.,  24 

Bank  loading,  shovel  for,  45 

Barker,  E.  E.,  160 

Bench  mining,  150 

Bench  work,  115-121 

height  of  banks,  116 

pit  slopes,  120 

slides,  121 

width  of  benches,  120 
Bessemer  Limestone  Co.,  75 
Biwabik  Mine,  crusher  plant,  112 

steam  shovel  used  at,  3 
Blacksmith  shop  and  forge,  106 
Blasting,  135-166 

See  also,  drilling  and  blasting. 


Block-caving,  201 

holing,  98,  152 
Boiler  for  steam  shovel,  12 
Boom  of  steam  shovel,  8 
Booms,  extra  long,  23 
Box  cuts,  121 
Branch-raise     system     of     mining, 

202 

Breaking  oversize  material,    152 
Bucket  excavator,  38 
Bucyrus  Company,  3,  5,  24,  28,  32, 

34,  40 
Bucyrus  drazline  excavators,  210 

engine,  13 
Bucyrus  shovel,  25,  48,  127,  226 

table  of  dimensions,  15 
Buffalo  &  Susquehanna  iron  mine, 

171 

Buffalo  mine,  125 
Buruettizing  ties,  90 
Burning  bottom,  98 
Butting  the  cut,  123 

Canadian  Klondyke  Mining  Co.,  33 
Capacity  of  dipper  of  steam  shovel,  9 
Car  frame  of  shovel,  6 

shops,  106 

Carbon  Hill  mine,  127 
Card  process  of  treating  ties,  90 
Carpenter  shop,  107 
Cars,  coaling,  103 
employees',  103 
flat,  103 

Cars  for  mining,  75-82 
dumping  type,  76 
hand-dumped,  vs.  air-dumped, 

77 

gondola  type,  76,  81 
hopper  bottom  type,  81 
ore  cars,  81 
stripping,  75-81 
powder,  103 


251 


252 


INDEX 


Cars,  large,     economy  of,  169 
repair,  102 

Casparis  Stone  Co.,  73,  75 

Casparis,  W.  R.,  74 

Cement  rock,blast  records  in,  146, 147 

Chain  haulage,  171 

Chamberlain,  O.  P.,  73 

Charges,  calculation  of,  153 

Charts  of  costs,  229 

Chile  Copper  Company,  5,  94,  160 
operating  costs,  223 

Chile  Exploration  Co.,  33 

Chino  Copper  Company,  5,  125,  136, 

138,  141 

cost  of  operation,  217,  221 
crusher  plant,  110 

Churn-drills,  93,  136,  140 

Clark  Car  Co.,  81 

Coal   mining    Bucyrus  shovel  used 

in,  25 
continuous-bucket   excavator 

used  in,  38 
hydraulicking,  179 
inclined  planes,  128-134 
machine  drilling,  140 
methods  in  Germany,  128 
steam  shovel  used  in,  3,  5 
stripping  method,  213 
tees  and  wyes,  125 
wasteful  methods,  213 

Coaling  car,  103 

Coarse    crusher    plant    of    Biwabik 

Mine,  112 
of  Chino  Copper  Co.,  110 

Coarse  crusher  plants,  110-113 

Commodore  mine,  187 

Compressed  air  for  pit  mining,  50 
locomotives,  66 

Connelly  Frog  Co.,  92 

Construction  of  standard  shovel,  12 

Continuous-bucket  excavator,  38 

Continental    Car    and    Equipment 
Co.,  81 

Copper  Mining,  bench  work  in,  115- 

121 

branch-raise  system,  202 
churn  drills,  141-146 
cost  of  supplies,  217 
statistics,  217-224 


Copper  Mining,  drilling  and  blast- 
ing, 150 
methods,  136 
dumps,  176,  178 
gopher  holing,  158,  160 
grade  of  ore  and  profit,  rela- 
tion of,  203 
steam  shovel  used  in,  5 
switchbacks,  125 
wage  scale,  217 
Cordean-Bickford   detonating    fuse 

147,  153,  155,  158 

Cost  of  compressed-air  haulage,  68 
locomotives,  65 
operation,  computing,  190 
preliminary  work  in  mining,  198 
shovel  equipment,  51 
Cost  of  shovel  work,  216-239 
annual  reports,  238 
Anthracite  stripping,  226 
brown-coal   mining    in     Ger- 
many, 227 

Chile  Copper  Co.,  223 
Chino  Copper  Co.,  221 
Granby  mine,  226 
keeping  records,  228 
Mesabi  iron  ore,  224 
monthly  statistics,  235 
Nevada  Consolidated  Copper 

Co.,  218,  228 
office  tabulations,  233 
Ontario  hydro-electric    canal 

job,  226 

Panma  canal,  228 
Utah  Copper  Co.,  220 
Yukon  Gold  Co.,  227 
Cost  of  supplies  increase,  217 
Course-stacking,    123-125 
Crews,  distribution  of,  168 
Cross-sections  of  ore-body,  246 
Crowding,  definition,  6 

engine,  10 

Crusher  plants,  coarse,  110-113 
Cyclone  drills,  93,  94,  161 

Danville,  111.,  hydraulicking,   179 
Davenport,  L.  D.,  123,  172 
Dehesa  mine,  125 
Denver  Co.,  97 


INDEX 


253 


Determination   of   a  power   shovel 

mine,  180-215 

example  of  solution  of  a  prob- 
lem, 193 

local  costs  and  conditions,  190 
maps  and  sections,  180 
preliminary  data,  180-193 
shovel  methods,  consideration 

of,  196 

special  problems,  209 
Detonators,  155 

Dimensions  of  Bueyrus  shovels,  15 
Marion  shovels,  23 
railroad  type  of  shovel,  16 
revolving  shovels,  19-22 
Dionisio  mine,  125 
Dipper,  9 

dredge,  37 
handle,  9 

extra  long,  23 
Vanderhoef,  10 

Disposal  of  material,  167-179 
dumps,  172-179 
transportation,  167-172 
Dobying,  98 

Dolese  &  Shepard  Co.,  73,  75 
Dragline  excavators,  38-43,  51 
cost,  52 

of  work,  226 
Dredges,  37 

Drilling  and  blasting,  135-166 
air  machines,  139 
blast  records,  146 
block  holing,  152 
breaking    oversize    material, 

152 

care  in  use  of  explosives,  166 
charges,  calculation  of,  153 
churn  drills,  140-157 
detonators,  155 
explosives,  152 
gopher  holes,  157-164 
hand-drills,  135-136 
machine  drills,  136-140 
Panama  Canal  methods,  138 
safety  rules,  156 
shooting  systems,  150 
single  and  multiple  hole  shots, 
139 


Drilling    and  blasting,    spacing    of 

holes,  149 

storing   and   thawing   explo- 
sives, 164-165 
tamping,  156 
tunnel  blasting,  161 
Drills  for  mining,  93-99 
block-holing,  98 
churn-drills,  93,  140-157 
tripod  drills,  97 
Dump  plows,  102 

site,  estimating  cost  of  trans- 
portation to,  169 
Dumps,  168,  172-179 
caved  ground,  176 
copper  mine,  176 
escarpment,  172 
height  of,  177 
hillside,  172 
hydraulicking,  178 
lake,  175 

Mesabi,  operations  on  the,  173 
slush,  175 
swamp,  175 
trestle,  174 

Du  Pont  Powder  Co.,  164 
Dynamites,    153.     See    also    Explo- 
sives. 

Electric  driven  shovels,  30 

exploders,  155 
Electric  haulage  system,  Wordford, 

69-75 

lighting  for  night  work,  99 
locomotives,  69-75 

Woodford  haulage  system,  69 
power  for  pit-mining,  47 
shovel,  47 

cost  of  operation,  34 
Electricians'  shop,  107 
Electro-hydraulic-driven  shovels,  35 
Employees'  car,  103 
Engine  and  car  shops,  106 
Engineering  work,  246 
Engines,  10 

Equipment,  distribution  of,  168 
Equipment  for  mining,  44-114 
balance  in,  107 
cars,  75-82 


254 


INDEX 


Equipment  for  mining,  coaling  and 
powder  cars,  103 

coarse   crusher  plants,    110- 
113 

drills,  93-99 

dump  plows,  102 

employees'  car,  103 

foundry,  107 

life  of,  109 

lighting  for  night  work,  99 

locomotive  crane,  102 

locomotives,  53-75 

machine  shop,  104 

ore  dryers,  113 

pumps,  99 

repair  car,  102 

shops,  103-107 

shovels,  45-53 

telephones  and  signals,  101 

track,  82-93 

wagons  and  trucks,  103 
Erie  shovel,  26 
Escarpment  dumps,  172 
Estimating  profits  from  mining,  203 
Excavation,  classes,  115 

methods,  115-134 
Excavators,   continuous-bucket,    38 

dragline,  38-43 
Explosives,  152,  153 
care  in  use  of,  166 
storing  and  thawing,  164 

Fayal  mine,  125 

Flat  cars,  103 

Forges,  106 

Foundry,  107 

Frame  of  steam  shovel,  6 

Gelatin  dynamites,  153 

powder,  142 
Gelignites,  153 
Genoa  mine,  128 

Germany,  cost  of  brown-coal  mining, 
227 

hydraulicking  in,  178 

mining  methods,  128 

pit  haulage,  171 
Gold  mining,  costs,  227 
Goodwin  dump-car,  78 


Gopher  holes,  157-164 

Granby  mine,  226 

Graphic  records  of  costs,  228 

Halby  shovel,  27 
Hall,  H.  H.,  227 
Hand-drills,  135 

stripping,  3 
Haulage  system,  Woodford  electric, 

69-75 

Height  of  banks  in  bench  work,  116 
Helms,  D.  C.,  129 
Hercules  powder,  146 
Hesler  locomotive,  54,  66 
Hibbing,  dumps  at,  177 
Hohan  Stone  Co.,  73 
Hoisting,  definition,  6 

engine,  11 

planes,  129 
Holes,  shooting,  150 

spacing,  in  drilling,  149 
Hull-Rust  mine,  125 
Hydraulic  dredge,  37 
Hydraulicking,  178 
Hydro-Electric  Power  Commission, 
see  Ontario  Hydro-Electric 
Power  Commission 

Illumination  for  mining  at  night,  99 
Inclined  planes,  128-134 
Ingersoll-Rand  Co.,  97,  105 
Ingersoll-Rand  drill,  139,  140 
Ingoldsby  type  of  car,  81 
Interstate   Commerce   Commission, 
on    storage    of    explosives, 
165 

Iron  mining,  bench  work  in,  115-121 
cost  of  operation,  224 
drilling,  135 
.  pit  haulage,  170 
See  also  Mesabi  iron  mines. 

Jack-arms,  8 
Jackhammer  drill,  98,  99 
Judson  powders,  153 

Keystone  Electric  drills,  93, 94,97, 161 
Kilbourne  &  Jacobs  Co.,  78,  81 
Klondike  mines,  costs,  227 


INDEX 


255 


Labor,  247 

Lake  dumps,  175 

Lake  Shore  Engine  Works,  27 

Laurin  &  Leitch  Co.,  75 

Leyner  drill,  97 

Lidgerwood      Manufacturing      Co., 

76 

Life  of  equipment,  109 
Lighting  for  night  work,  99 
Lima  Locomotive  Works,  66 
Limestone  quarry  blast  records,  146- 

149 

shooting  holes,  150 
Locomotive  crane,  102 
Locomotives,  selection  of,  53—75 
compressed  air,  66 
cost,  65 
determination      of      tractive 

force,  55 
direct-connected  steam  type, 

54 

draw-bar  pull,  56 
electric,  69-75 
factor  of  adhesion,  55 
fuel  and  water  consumption, 

64 

geared  types,  66 
hauling  capacity,  58-63 
horse-power,  63 
resistance  due  to  curves,  57 
grades,  56 
rolling  friction,  56 
sizes  for  open  pit  work,  64 
steam    and    compressed    air 

compared,  68 
Locust  Mt.  Coal  Co.,  33 
Los  Angeles  Board  of  Public  Works, 

33 
Lowry  process  of  treating  ties,  90 

Machine-drills,    136 

shop,  104 
Mahoning-Hull-Rust  orebody,  costs 

of  operation,  225 
mine,  125 

Mallet  type  of  ore  car,  81 
Mapping    a    power     shovel    mine, 

180 
Marble  Cliff  Quarries  Co.,  75 


Marion  dragline  excavator,  38 
revolving  shovel,  13,  127 

dimensions,  23 

Marion  Steam  Shovel  Co.,  17,  24,  33 
Mechanical  development  of  steam 

shovel,  5 

equipment  for  mining,    44-114 
See    also    Equipment    for 
mining. 
Mesabi  iron  mines,  Biwabik  crusher 

plant,  112 

circular  stripping,  127 
costs  of  operation,  224 
distribution  of  crews,  168 
drilling  footage,  139 
dumps,  172-174,  176-178 
engineering  work,  246 
equipment,  109 
gopher-holing,  158 
height  of  benches,  119 
labor,  247 

locomotives  used,  65 
ore  dryers,  113,  114 
pit  haulage,  170 
powder  magazines,  164 
salt  solution  for  thawing,  169 
shovel,  first  used,  3 
spiral  pit  systems,  125 
stripping  cars  used,  78 
stripping  ore  body,  245 
switchback  system,  125 
thorough  cut  mining,  123 
track  shifter  used,  86 
Methods  of  attack,  115-134 
Michigan  Alkali  Co.,  75 
Milling  system,  134 
Mines,  maps  and  sections,  180 
Mining,  administration,  240-249 
costs,  219,  221,  223,  224 
history  of  early  operations,  1 
mechanical  equipment  for,  44- 

114 

methods  of  attack,  115-134 
power  for,  47-51 
Mining  methods,  115-134 
bench  work,  115-121 
block-caving,  201 
branch-raise  system,   202 
casting  over,  121 


256 


INDEX 


Mining    methods,     course-stacking, 

123-125 

determination  of,   180-215 
disposal    of    material,    167- 

179 

inclined  planes,  128-134 
milling  systsm,  134 
open-cast  work,  1-3 
pit  layouts,  125-134 
shrinkage-stope,  200 
spirals,  125 
switchbacks,  125 
tees  and  wyes,  125 
thorough  cut,  121-123 
top-slicing,  200 
tunnels  and  shafts,  127 
underground,  200-203 

Mission  Mining  Company,  5 

Missouri  Iron  Co.,  75 

Moore,  H.  W.,  160 

Mud-capping,  98,  152 

Myers- Whaley.  shovel,  27 

Nevada  Consolidated  Copper  Co., 
5,  45,  95,  125,  142-146,  161, 
173,  185 

cost  records,  228 
operating  costs,  218 
wage  scale,  217 
Niles  Bement  Pond  Co.,  105 

Office  tabulations  of  costs,  233 
Oil-engine-driven  shovels,  37 

engines,  for  pit  mining,  50 
Oklahoma    Portland    Cement    Co., 

75 

Oliver  Manufacturing  Co.,  81 
Ontario  Hydro-Electric  Power  Com- 
mission, 5,  33,  172 
canal,  cost  of  work,  226 
Open-cast  work,  1-3 

pit  work,  slides,   121 
Operating  costs  of  Chile  Copper  Co., 

223 

Chino  Copper  Co.,  217,  221 
Nevada  Consolidated  Copper 

Co.,  218 
Utah  Copper  Co.,  220 


Ore  cars,  81 

dryers,  113 

mining,  electric  shovels  used  in, 

34 

Oswego  shovel,  3 
Otis  Company,  5 
Overburden,  routing  of,  168 

Panama  Canal,  costs,  228 

drilling  methods,  138 

Parker  shovel,  14 

Parsons  trench  excavator,  38 

Patnol,  G.  W.,  73 

Paynter  drill,  106 

Penn  Iron  Mining  Co.,  36 

Pit  haulage,  170 

Pit  layouts,  125-134 

inclined  planes,  128-134 
milling  system,  134 
spirals,  125 
switchbacks,  125 
tunnels  and  shafts,  127 

Pit  slopes  in  bench  work,  120 

Pittsburg  &  Midway  Coal  Co.,  33 

Pittsburg  Iron  Co.,  114 

Placer-dredges,  37 

Porter  Co.,  H.  K,  63,  65 

Powder  car,  103 
magazines,  164 

Powders,  153 

Power   &    Mining    Machinery   Co., 
Ill,  112 

Power  for  pit  mining,  47-51 

Power-shovel    mine,    determination 
of,  180-215 

Power  shovels,  1-43 

electric  driven,  30-35 
electro-hydraulic  driven,  35 
oil-engine-driven,  37 
steam  shovels,  1-30.    See  also 
Steam  shovels.. 

Profit  from  copper  mining,  calculat- 
ing, 203 

Pullman  Co.,  81 

Pumps  for  mining,  99 

Quarry  blast  records,  146-149 
shovels,  24 


INDEX 


257 


Railroad  type  of  shovel.  14 

dimensions,  16 
Records  of  cost,  keeping,  228 
Red  Cross  powder,  144,  147 
Repair  car,  102 
Repairs,  cost  of,  109,  110 
Revolving  shovels  cost,  52 

dimensions,  19-22 
steam  shovels,  17 

used  in  coal  mining,  5 
Rio  Tinto  Company,  3,  5,  125 

open-cast  work  at,  1-3 
Robinson,  J.  W.,  199 
Robinson  shovel,  27 
Rock  Hill  Co.,  97 
Rogers,  H.  W.,  35,  48 
Ropauno   Gelatin   Dupont  powder, 

142 

Routing  of  overburden,  168 
Rueping  process  of  treating  ties,  90 
Russell,  S.  R.,  146,  153,  157 

Safety  measures,  248 

rules  for  blasting,  156 
Salt  solution,  use  of,   for  thawing, 

169 

Schroeder  Headlight  Co.,  101 
Sections  of  a  mine,  making,  180 

of  ore-body,  246 
Selection  of  shovels,  45-53 
Shafts,  127 

Shay  locomotive,  54,  66 
Shenango  Furnace  Co.,  114 
Shenango  iron  mine,  125,  170 
Shipping  a  shovel,  12 
Shops,  103-107 
Shooting  well-drill  holes,  150 
Shovel  excavation,  classes,  115 

methods,  consideration  of,   196 

work,  cost  of,  216-239 
Shovelling  machines,  27 
Shovels,  cost  of  equipment,  51 

electric,  47 

electric  driven,  30 

electro-hydraulic-driven,  35 

oil-engine-driven,  37,  50 

revolving,  cost,  52 

selection,  for  mining,  45-53 

steam.    See  Steam  shovels. 

17 


Shrinkage-stope  methods  of  mining, 
200 

Signals  in  mining  plants,  101 

Slides  in  open  pit  work,  121 

Slush  dumps,  175 

Snake-holing,  152 

Spacing  of  holes  for  drilling,  149 

Spain,  early  mining,  operations  in,  1. 
See  also  Rio  Tinto  Co. 

Spirals,  125 

Star  drills,  93,  94 

Steam  power  for  pit  mining,  47 

Steam  shovels,  1-30 

booms     and    dipper-handles, 

extra  long,  23 
Bucyrus  coal  excavator,  25 
coal  mining,  with,  3,  5 
competing  machines,  37 
construction  of  standard,  12 
copper  ore  mining,  5 
description  of  standard,  6-12 
early  application,  3 
Erie  type,  26 
invention  and  patents,  5 
life  of,  109 

mechanical  development,  5 
quarry,  tunnel,  and  stope.  24 
railroad  or  standard  type,  14 
revolving,  5,  17 
strain  diagram,  9 
Thew  type,  24 
wire-rope,  27 

Steel  used  in  shovels,  12 

Stephenson  link  motion,  11 

Stevenson  mine,  125 

Stope  shovels,  24 

Strain  diagram,  9 

Stripping  cars,  75-81 

costs,  218,  221,  223,  224,  226 
in  anthracite  regions,  129 
methods  of  coal  mining,  213 
prepaid,  245 

Sturtevant  Co.,  B.  F.,  105 

Suction  dredge,  37 

Sullivan  Co.,  97 

Swamp  dumps,  175 

Swinging,  definition,  6 
engine,  11 

Switchbacks,  125 


258 


INDEX 


Tabulations  of  costs,  233 

Tamping,  156 

Taxes.     See  Cost  of  shovel  work. 

Tees  and  wyes,  125 

Telephones  in  mining  plants,  101 

Temescal  Rock  Co.,  75 

Temple-Ingersoll  drill,  98,  140 

Tharsis  Company,  3,  128 

Thawing  explosives,   164 

Thew  Automatic  Shovel  Co.,  24,  50 

Thew  shovels,  24 

cost,  53 

Thorough  cut,  121-123 
Thrusting  engine,  10 
Topographic  map,  183 
Top-slicing,  200 
Track  for  mining,  82-93 

alignment,  83 

angle  bars  and  fastenings,  89 

curves,  83 

definitions  and  rules,  82 

frogs  and  switches,  91 

gauge,  84 

general  pit-track,  82 

maintenance,  85 

materials  and  equipment,  87 

protective  devices,  92 

rails,  87 

spikes,  89 

tie  plates,  89 

ties,  90 

tools,  90 

Trackage     arrangements     for     dis- 
posal of  material,  167 
Transportation  of  material,  167-172 

delays,  167 

distribution  of  crews,  168 
•of  equipment,  168 

economy  of  large  cars,  169 

estimating  cost  to  new  dump, 
169 

pit  haulage,  170 

routing  of  overburden,  168 

salt  solution,  use  of,  169 

trackage   arrangements,    167 


Trestle  dumps,  174 

Tripod  drills,  97 

Trojan  powder,  142,  145,  146 

Tromberg  Carlson  Co.,  102 

Trucks,  103 

Tunnel  shovels,  24 

Tunnels,  127 

blasting  from,   161 

Underground    methods    of    mining, 

200-203 

United  Verde  Copper  Co.,  33 
Utah  Copper  Company,  5,  94,  100, 

119,  136,  141,  158,  171,  173 
cost  of  operating,  220 

Van  Barneveld,  C.  E.,  134 

Vanderhoef  dipper,  10 

Virginian  Limestone  Corporation,  75 

Wage  scale  in  copper  mining,  217 

Wages.     See  Cost  of  shovel  work. 

Wagons,  103 

Warriner,  J.  B.,  129,  213,  226 

Waste  haul,  168 

Waugh  Turbo  drill,  97 

Well-drill  holes,  146-152 

Well-drills,  140 

Wellhouse  process  of  treating  ties,  90 

Western  Electric  Co.,  102 

Western  Wheeled  Scraper  Co.,  78,  81 

Westinghouse  Electric  Co.,  101 

Westinghouse-Pacific    Coast    Brake 

Co.,  98 

Wire-rope  shovels,  27 
Wood  process  of  treating  ties,  90 
Woodford,  F.  E.,  69       . 
Woodford  electric  haulage  system, 

69-75 

Young,  J.  G.,  171 
Yukon  Gold  Co.,  227 

Zarza  lode,  3,  128 


Vr*      O  •o^cr  I 

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DEPT.  OF  MINING  &  METALLURGY 


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